In recent years, the need to reduce environmental impacts and increase flexibility in the energy sector has led to increased penetration of renewable energy sources and the shift from concentrated to decentralized generation. A fuel cell is an instrument that produces electricity by chemical reaction. Fuel cells are a promising technology for ultimate energy conversion and energy generation. We see that this system is integrated, where we find that the wind and photovoltaic energy system is complementary between them, because not all days are sunny, windy, or night, so we see that this system has higher reliability to provide continuous generation. At low load hours, PV and electrolysis units produce extra power. After being compressed, hydrogen is stored in tanks. The purpose of this study is to separate the Bahr AL-Najaf Area from the main power grid and make it an independent network by itself. The PEM fuel cells were analyzed and designed, and it were found that one layer is equal to 570.96 Watt at 0.61 volts and 1.04 A/Cm². The number of layers in one stack is designed to be equal to 13 layers, so that the total power of one stack is equal to 7422.48 Watt. That is, the number of stacks required to generate the required energy from the fuel cells is equal to 203 stk. This study provided an analysis of the hybrid system to cover the electricity demand in the Bahr AL-Najaf region of 1.5 MW, the attained hybrid power system TNPC cost was about 9,573,208 USD, whereas the capital cost and energy cost (COE) were about 7,750,000 USD and 0.169 USD/kWh respectively, for one year.

The generation of entropy and mixed convection in a nanofluid-filled 3D wavy tank containing a rotating cylinder is investigated. The top wavy surface of the tank is heated and all vertical surfaces are assumed to be adiabatic, while the bottom horizontal surface remains isothermally cold. The tank contains a solid cylinder and is saturated with an Al₂O₃–water nanofluid. The numerical simulations using the FEM are performed for the Richardson number ($0.01\le Ri\le 100$), nanoparticle volume fraction ($0\le \varphi \le 0.04$) and number of oscillations ($0\le N\le 4$). The numerical results of the present work are given in terms of 3D streamlines, isotherms and local entropy generation, as well as average heat transfer and Bejan number. The results show that for low values of the Richardson number and oscillation, heat transfer enhancement can be achieved by increasing the nanoparticle volume fraction.

It can be considered that the solar collector is an essential thermal device, and it can be used to utilize solar energy via collecting and concentrating solar radiation. This system has many applications, such as water heating, building heating and other industrial applications. In this work, two new systems of heat pipe evacuated tube solar collector (HP-ETSC) were built. The first one was integrated with phase change material (PCM) and the second one without PCM. The first part investigated the effect of integrating PCM on the behavior and performance of HP-ETSC. While in the second part, the influence of applying vibration with different frequencies on the system to enhance the system’s overall performance and efficiency was studied. All executed tests were done in Iraq and during the winter season. It selected four cases, (1) system without integrated PCM, without applying vibration; (2) system without integrated PCM, with applying vibration; (3) system with integrated PCM, without applying vibration; (4) a system with integrated PCM, with applying vibration, to find the optimal system of them. The results proved that the system’s performance was enhanced.