Abstract
The proton exchange membrane fuel cell (PEMFC) is regarded as the most competitive candidate to replace the traditional forms of power conversion due to its prominent advantages. Th hydrogen gas is used as a main fuel in the fuel cells. Th hydrogen gas can be produced through the use of solar energy which is connected to alkaline electrolysis cell (AEC) by water splitting process known as electrolysis. In this paper, a thermodynamic model is presented to design and optimize a direct coupling system (DCS) that has twocells, an alkaline electrolysis cell (AEC) and a proton exchange membrane fuel cell (PEMFC). Moreover, the performances of the direct coupling system (DCS) are evaluated using numerical model that are built in Engineering Equations solver softare. So several parameters concerning the direct coupling system (DCS) such as the voltage of system, the hydrogen rate production from electrolysis which injects to fuel cell and producing power of the full system. Th simulations result show that, the voltage of alkaline electrolysis is higher than the fuel cell. Th water management process in the whole system is considered satisfactory due tothe low value of the losses in the amount of water. Th water which is generated from the fuel cell is injected to electrolysis cell, so the electrolysis cell does not need to inject large quantities of water. Th effiency of the system is about 34.85% and this effiency is satisfactory compared to other systems of power generation as this percentage is due to clean, renewable and environmentally friendly fuel.

Key words: Renewable energy, alkaline electrolysis cell (AEC), the proton exchange membrane fuel cell (PEMFC), power generation