Modeling of an alkaline electrolyzer and a proton exchange membrane fuel cell (PEMFC) is presented. Also, a parametric study\r\nis performed for both components in order to determine the effect of variable operating conditions on their performance. The\r\naim of this study is to determine the optimum operating conditions when the electrolyzer and the PEMFC are coupled together\r\nas part of a residential solar powered stand-alone power system comprising photovoltaic (PV) arrays, an alkaline electrolyzer,\r\nstorage tanks, a secondary battery, and a PEMFC. The optimum conditions are determined based on an economic study which\r\nis performed to determine the cost of electricity (COE) produced from this system so as to determine the lowest possible COE.\r\nAll of the calculations are performed using a computer code developed by using MATLAB. The code is designed so that any user\r\ncan easily change the data concerning the location of the system or the working parameters of any of the system�s components to\r\nestimate the performance of a modified system. Cairo city in Egypt was used as the place at which the output of the system will be\r\ndetermined. It was found that the optimum operating temperature of the electrolyzer is 25?C. Also, the optimum coupling pressure\r\nof the electrolyzer and the PEMFC is 4 bars. The operating temperature of the PEMFC had a slight effect on its performance while\r\nan optimum current density of 400 mA/cm2 was detected. By operating the fuel cell at optimum conditions, its efficiency was\r\nfound to be 64.66% with a need of 0.5168Nm3 (Nm3 is a m3 measured at temperature of 0?C and pressure of 1 bar) of hydrogen\r\nto produce 1kWh of electricity while its cogeneration efficiency was found to be 84.34%. The COE of the system was found to be\r\n49 cents/kWh, at an overall efficiency of 9.87%, for an operational life of 20 years.
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