Techno-economic assessment of a repowering scheme for a coal fired power plant through upstream integration of SOFC and downstream integration of MCFC

A thermodynamic and economic assessment of an innovative scheme to repower a thermal power plant is presented here. A solid oxide fuel cell (SOFC) plant is incorporated at upstream of the present boiler and a molten carbonate fuel cell (MCFC) plant is incorporated at downstream of present boiler. Coal feeds are reduced (reduction varied from 10% to 40%) by partially off-loading the mills. Energy, equivalent to that replaced coal, is provided by the exhaust of the direct internal reforming (DIR) SOFC which runs on natural gas. The MCFC plant also consumes some fresh natural gas and separates CO2 from the boiler exhaust. The proposed model, developed and analyzed using Cycle Tempo software, yields better performance while substantially increasing the plant capacity (more than 50%) and reducing the CO2 emission (90%). The findings suggest that at 20% coal replacement the plant becomes most economical, offering electricity at an estimated unit cost of USD 84/MWh, as against USD 111/MWh for MEA retrofitted plant.