The current research examined and compared two new hydrogen production systems as well as optimization procedures to determine the best optimum conditions. Developed systems include two integrated systems in one of them a vanadium chloride cycle is used to produce hydrogen from biogas and the other a proton exchange membrane electrolyzer (PEME) is used. Both suggested systems are integrated with a solid oxide fuel cell (SOFC) and an anaerobic digester (AD). A parametric investigation is performed on the systems to determine the effects of changing parameters such as solid oxide fuel cell temperature, fuel cell working pressure, current density, and utilization factor the thermodynamic, economic, and environmental performance of the systems. Findings indicated that the current density of 0.54 was about 5.5 % higher than the system with electrolysis, while the cost rate of the system was 22% percent lower. With the change of SOFC temperature from 900 K to 1300 K, the results showed that in 1000 K, the emission reach 0.273 kg/kWh, which was the lowest value. Moreover, by enhancing the utilization factor from 0.65 to 0.9, the amount of pollution in the system with vanadium chloride cycle was reduced by 24%, which the reduction for the system with PEME was about 20%. Carried out analysis based on the thermodynamic, economic, and environmental index indicated a multi-objective optimization for studied systems. Both developed systems were optimized and the best performance conditions were determined based on the definition of the ideal point.
