Performance study of solar aided molten carbonate fuel cell-steam turbine-combined cooling, heating and power system with different schemes

Abstract

The efficient use of solar energy and fuel cells has become an important way to achieve the goal of “carbon neutral” power generation. This paper firstly proposes a new molten carbonate fuel cell-steam turbine-combined cooling, heating and power (MCFC-ST-CCHP) system. In order to further improve the performance of the MCFC-ST-CCHP system, three solar aided MCFC-ST-CCHP systems with different solar energy integration modes are proposed in this paper. Solar energy is used to drive the methane dry reforming reaction or replace part of the heating load of high pressure boiler drum or high pressure economizer in heat recovery steam generator. The performances of different systems are studied and compared. The results show that the energy efficiencies, the exergy efficiencies and the specific CO2 emission rates of three systems are 65.89%, 63.77%, 480.79 g/kWh; 66.25%, 65.12%, 477.93 g/kWh; and 65.86%, 64.88%, 481.08 g/kWh, respectively. The best solar integration mode is to replace part of the heating load of high pressure boiler drum. The impact of solar irradiation intensity on new solar aided MCFC-ST-CCHP system with the best solar integration mode further investigated. The results show that when the direct normal irradiance (DNI) of solar energy changes throughout the day, the new system’s solar heat collection efficiency, solar power generation and solar-to-electricity efficiency increase first and then decrease, and the specific CO2 emission rate of the system decreases first and then increases.