Integration of biomass-fueled power plant and MCFC-cryogenic CO2 separation unit for low-carbon power production: Thermodynamic and exergoeconomic comparative analysis

Abstract

Bio-Energy with Carbon Capture and Storage (BECCS) system is emerging as a promising technology to support the development of low carbon power systems. In this context, the present research proposes two scenarios to obtain a biomass-fueled power plant with limited CO2 emissions. A novel combination of a downdraft gasifier (DG), internally fired gas turbine, Molten Carbonate Fuel Cell (MCFC), Organic Rankine Cycle (ORC), and cryogenic separation unit, is proposed (named scenario 1) and it is compared to a system in which a bottoming steam cycle (SBC) was used instead of the ORC (named scenario 2). To have a deeper insight into the performance of the integrations, a sensitivity analysis and comparative study have been developed in this research in terms of their thermodynamic and economic performance. Sensitivity analysis explores the effects of significant variables on the proposed system performance: fuel cell current density, fuel cell steam to carbon ratio, gas turbine inlet temperature, and CO2 and fuel utilization factors.Exergy and exergoeconomic analyses reveal that the air-preheater in scenario 1 and gasifier in scenario 2 are identified as the component with maximum exergy destruction rate (21% and 14% of total respectively) and HRU in scenario 1 and SBC condenser have the lowest value of the exergoeconomic factor (3.76% and 0.01% respectively) due to high thermodynamic inefficiencies, while MCFC in both scenarios has the highest exergoeconomic factor 87.29% and 80.67% respectively due to its high investment cost. Also, scenario 1 achieves the amount of 83.86 (USD/MWeh) for LCOE that is 55.76 (USD/MWeh) more than the reference case and 3.55 (USD/MWeh) less than the scenario 2.