Effect of blending hydrogen to biogas fuel driven from anaerobic digestion of wastewater on the performance of a solid oxide fuel cell system

摘要

Fuel composition is proved to have a significant influence on the performance of solid oxide fuel cell (SOFC) systems. In the present research, the effect of hydrogen injection to biogas-fed SOFC power systems is investigated. Hydrogen production is performed through implementing a Photovoltaic-based solar system to electrolyze water by means of a Proton Exchange Membrane (PEM) electrolyzer. In the present research, waste water as the primary source of energy is chosen to drive a novel integration of photovoltaic with SOFC systems. For comparison reasons, two cases depending on the hydrogen storage scenario or hydrogen utilization in the SOFC system are developed. Thermodynamics and exer-goeconomic models have been developed to analyze the performance of proposed systems. Results indicate that increasing the molar ratio of hydrogen in the biofuel mixture up to 0.35 increases the SOFC cell voltage and the system net output power up to 4%. Also, due to the certain advantages of hydrogen, blending hydrogen with biogas results in a reduction of CO_2 emission by 16%. The overall efficiency of the system, when the produced hydrogen is totally stored in the storage tank, would be higher than that of the system where the produced hydrogen is partially utilized in the SOFC system. The economic analysis revealed that the unit product cost of the system shows approximately a linear reduction with an increase in the hydrogen amount of the fuel.