Integrating a High Temperature Fuel Cell with СО₂ Capture System into Thermal Power Plant Energy Cycle

Abstract

The molten carbonate fuel cell allows for capturing, separating and concentrating CO2 as it passes through the carbonate melt from the cathode side to the anode side, while simultaneously generating electricity and heat. The article presents the technology and flow diagram of a system for capturing CO2 from flue gases of a thermal power plant in a high-temperature fuel cell on molten carbonates with subsequent conversion and utilization of gaseous combustible products in the energy cycle of a thermal power plant. The fuel cell runs on natural gas with internal reforming. After the fuel cell, the gas leaving the anode is sent to the conversion unit where, in reaction with carbon at high temperatures, combustible gases are formed that are suitable for re-combustion in the turbine. For power plants and a system for capturing and converting carbon dioxide, thermodynamic, technical and economic calculations were carried out. The efficiency of a high-temperature fuel cell is 42 %. In the baseline scenario, the net energy efficiency of the plant is 61 % while a CO2 capture ration is 80–85 %. The return of fuel gases after the conversion of carbon dioxide, taking into account their calorific value, makes it possible to additionally increase the electric power of the thermal power plant up to 20 %. With a unit cost of a fuel cell of 1300 EUR/kW and a price of natural gas of 0.04 EUR/kW, the total electricity cost of the plant is 0.074 EUR/kW. The results show that the proposed system is attractive for natural gas power generation with CO2 capture.