Performance analysis of a co-generation system using solar energy and SOFC technology

• A new concept of a cogeneration system is proposed and investigated.
• The system comprises solar collector, PV, SOFC and heat exchanger.
• 83.6% Power and heat generation efficiency has been found at fuel cell mode.
• 85.1% Efficiency of SOSE has been found at H2 production mode.
• The heat to power ratio of SOFC mode has been found about 0.917.

Due to the increasing future energy demands and global warming, the renewable alternative energy sources and the efficient power systems have been getting importance over the last few decades. Among the renewable energy technologies, the solar energy coupling with fuel cell technology will be the promising possibilities for the future green energy solutions. Fuel cell cogeneration is an auspicious technology that can potentially reduce the energy consumption and environmental impact associated with serving building electrical and thermal demands. In this study, performance assessment of a co-generation system is presented to deliver electrical and thermal energy using the solar energy and the reversible solid oxide fuel cell. A mathematical model of the co-generation system is developed. To illustrate the performance, the system is considered in three operation modes: a solar-solid oxide fuel cell (SOFC) mode, which is low solar radiation time when the solar photovoltaic (PV) and SOFC are used for electric and heat load supply; a solar-solid oxide steam electrolyzer (SOSE) mode, which is high solar radiation time when PV is used for power supply to the electrical load and to the steam electrolyzer to generate hydrogen (H2); and a SOFC mode, which is the power and heat generation mode of reversible SOFC using the storage H2 at night time. Also the effects of solar radiation on the system performances and the effects of temperature on RSOFC are analyzed. In this study, 100 kW electric loads are considered and analyzed for the power and heat generation in those three modes to evaluate the performances of the system. This study is also revealed the combined heat and power (CHP) efficiency of the system. The overall system efficiency achieved for the solar-SOFC mode is 23%, for the solar-SOSE mode is 20% and for the SOFC mode is 83.6%. Besides, the only electricity generation efficiency for the solar-SOFC mode is 15%, for the solar-SOSE mode is 14% and for the SOFC mode is 44.28%. An economic analysis is presented based on the annual electricity generation from the system and the system has shown the good economic viability in this study with a unit cost of energy (COE) about 0.068 $/kW h.