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Experimental Methods for Engineers

Alkaline water electrolysis is a key technology for large-scale hydrogen production powered by renewable energy. As conventional electrolyzers are designed for operation at fixed process conditions, the implementation of fluctuating and highly intermittent renewable energy is challenging. This contribution shows the recent state of system descriptions for alkaline water electrolysis and renewable energies, such as solar and wind power. Each component of a hydrogen energy system needs to be optimized to increase the operation time and system efficiency. Only in this way can hydrogen produced by electrolysis processes be competitive with the conventional path based on fossil energy sources. Conventional alkaline water electrolyzers show a limited part-load range due to an increased gas impurity at low power availability. As explosive mixtures of hydrogen and oxygen must be prevented, a safety shutdown is performed when reaching specific gas contamination. Furthermore, the cell voltage should be optimized to maintain a high efficiency. While photovoltaic panels can be directly coupled to alkaline water electrolyzers, wind turbines require suitable converters with additional losses. By combining alkaline water electrolysis with hydrogen storage tanks and fuel cells, power grid stabilization can be performed. As a consequence, the conventional spinning reserve can be reduced, which additionally lowers the carbon dioxide emissions.

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Alkaline Water Electrolysis Powered by Renewable Energy: A Review

An investigation on solar drying: A review with economic and environmental assessment

Effect of operating parameters on hydrogen production by electrolysis of water

In this work, FeIr bimetallic alloy self-supported on nickel foam is prepared by hydrothermal method, with average particle size of 2.17 nm and the Ir-loading is only 0.936 wt.%. It displays ultralow overpotentials for OER (200 mV) and HER (16.6 mV) at 20 mA cm−2 in alkaline media, which is superior to the ever reported HER catalysts. For overall water splitting, it only needs 1.48 V to derive a current density of 10 mA cm−2, and it also demonstrates an outstanding long-term stability with an ignorable decline in performance after testing 504 h at the current density of 150 mA cm−2. The excellent performance is ascribed to the ultrasmall FeIr alloy, the 3D conductive substrate, and the ethylene-glycol ligand environment facilitates highly efficient HER through hydrogen spillover. Thus, this work undoubtedly provides a promising method for developing ultralow-loading noble metal catalysts with excellent performance at large current density for overall water splitting.

Bimetallic iron-iridium alloy nanoparticles supported on nickel foam as highly efficient and stable catalyst for overall water splitting at large current density

Hydrodynamics characteristics of hydrogen evolution process through electrolysis: Numerical and experimental studies

Investigating the performance of a twisted modified Savonius rotor

Modeling of wind turbine wakes under thermally-stratified atmospheric boundary layer

Alkaline water electrolysis is considered to be a basic technique for hydrogen production. Many researchers have investigated the alkaline water electrolysis in order to promote electrochemical reaction. In the present paper, the effects of voltage, electrolyte concentration and space between the pair of electrodes on the amount of hydrogen produced and consequently on the overall electrolysis efficiency are experimentally investigated. The experimental measurements are carried out by the present authors at the fluid mechanics laboratory of Menoufiya University. The alkaline water electrolysis of different potassium hydroxide aqueous solutions is conducted under atmospheric pressure using stainless steel electrodes. The experimental results showed that the performance of water electrolysis unit is highly affected by the voltage input and the gap between the electrodes. Higher rates of produced hydrogen can be obtained at smaller space between the electrodes and also at higher voltage input. Higher system efficiency was also gained at smaller gap distances between the pair of electrodes.

Experimental Investigation of the Operating Parameters Affecting Hydrogen Production Process through Alkaline Water Electrolysis

This paper investigates theoretically and experimentally the optimum operating conditions for alkaline water electrolysis coupled with a solar photovoltaic (PV) source for hydrogen generation with emphasis on the electrolyzer efficiency under different operating conditions. The PV generator is simulated using Matlab/Simulink to obtain its characteristics under different operating conditions with solar irradiance and temperature variations. A wide range of operating parameters, which include input voltage, temperature, concentration of the electrolyte, and distance between the electrodes, are considered, and their effects on the efficiency of hydrogen production process are explored. A group of performance curves for the solar-hydrogen energy system (SHES) under a wide range of operating conditions are obtained through a number of individual experimental measurements. The optimum operating conditions, which correspond to the maximum electrolyzer efficiency, are determined for the proposed SHES. The effects of the ambient temperature and the electrolyte temperature on the performance of the solar PV energy system and the hydrogen production process are also investigated.

I.M. Sakr

Papers

Hydrodynamics characteristics of hydrogen evolution process through electrolysis: Numerical and experimental studies

Investigating the performance of a twisted modified Savonius rotor

Modeling of wind turbine wakes under thermally-stratified atmospheric boundary layer

Experimental Investigation of the Operating Parameters Affecting Hydrogen Production Process through Alkaline Water Electrolysis

Optimum Operating Conditions for Alkaline Water Electrolysis Coupled with Solar PV Energy System