Hydrogen is considered one of the fundamental elements in the universe, carrying energy. Hydrogen is the most abundant element in the universe, accounting for approximately 75% of its baryonic mass (and about 90% of its atoms. It is found in water, the bodies of animals, plants, humans, and birds, as well as in petroleum and its derivatives, and in coal1. Electrolysis is a modern method for obtaining hydrogen from water. The Electrolyzer works by breaking down water into hydrogen and oxygen using electrical energy, which in the modern era is often obtained from renewable energy sources such as the sun and wind2. Once hydrogen is produced, it must be stored, transported, and reused safely. Therefore, this article discusses the optimal design of a water Electrolyzer, the necessary precautions, and the safety measures to be followed when producing, transporting, storing, and reusing hydrogen.
Electrolyzers are categorized according to their construction and operational features. Alkaline Electrolyzers (AEL), solid oxide Electrolyzers (SOE), and proton exchange membrane (PEM) Electrolyzers are the three primary types3. The maturity and affordability of alkaline Electrolyzers have led to their widespread adoption. It functions at moderate temperatures between 60 °C and 80 °C and use a liquid electrolyte, usually potassium hydroxide (KOH)4. Compact design and greater operating pressures are made possible by PEM Electrolyzers, which use a solid polymer membrane as the electrolyte. The optimal temperature range for these Electrolyzers is between 50 °C and 70 °C5. Lastly, SOE Electrolyzers use steam as the feedstock and run at much higher temperatures, between 600 °C and 1000 °C. Increased efficiency is possible with this high-temperature operation, although material stability issues arise6. Electrolyzer performance is determined by several important characteristics. Depending on the system’s kind and efficiency, the applied voltage usually falls between 1.8 and 2.5 volts per cell7. In8 a description of the design and performance evaluation of a novel 1 kW-class hydrogen production/power generation system is done. A crucial factor influencing the rates of hydrogen production, current density typically ranges from 0.2 to 2 amperes per square centimeter. Higher current densities can have a detrimental effect on durability and efficiency even when they increase production rates. Another crucial element is operation temperature; AEL systems run at lower temperatures than SOE systems, which need high heat to function at their best. These systems’ overall efficiency ranges from 60% to 80%, and research is still being done to increase this figure9.
Electrolyzer manufacture is a complex process. Electrode manufacture is a crucial stage that necessitates the use of robust materials, such as nickel, platinum, or iridium, which are frequently coated to improve catalytic performance10. While SOE Electrolyzers use ceramic materials for their electrolytes, PEM Electrolyzers depend on the creation of proton-conductive membranes11. After each part is ready, it is placed together into stacks with cells connected in series to produce the desired result. To guarantee that the stacks can endure operational pressures and temperatures while retaining durability over time, the last steps entail sealing and enclosing the stacks12. After hydrogen is created, it must be stored effectively to allow for its transportation and usage in a variety of applications. The purpose of hydrogen storage tanks is to securely hold hydrogen in either its liquid or gaseous state. The most popular are compressed gas tanks, which hold hydrogen at pressures between 350 and 700 bar13. Because of their lightweight construction and comparatively straightforward design, these tanks are frequently utilized in transportation applications. As an alternative, liquid hydrogen is stored in cryogenic tanks at very low temperatures, usually − 253 °C, which offers a higher energy density but necessitates sophisticated insulation to avoid boiling off14. Although they typically have smaller storage capacities, metal hydride tanks are another approach in which hydrogen is absorbed into metal alloys for safe storage at lower pressures15.
The use and storage technique dictate the requirements of hydrogen storage tanks. For high-pressure compression tanks, which are usually made of carbon fiber composites, material strength is very important1617. For transportable and portable tanks, these materials offer the required strength-to-weight ratio. In contrast, cryogenic tanks are typically constructed from aluminum alloys or stainless steel to provide structural integrity and efficient thermal insulation at low temperatures. The size and technology of the tank determine the storage capacity, which is usually expressed in kilos of hydrogen. Additionally, pressurized tanks need to be resilient to heat stress and wear to endure quick cycles of filling and discharging18. There are several clearly defined steps involved in the manufacturing of hydrogen storage tanks. The first step in the process for high-pressure tanks is to choose lightweight, strong materials, including carbon fiber composites19. The tank body is created by winding these materials around a core using sophisticated filament winding processes. For cryogenic applications, metallic tanks are molded or welded to exact specifications. To stop hydrogen leaks, a metal or polymer inner liner is incorporated into the tank20. To make sure the tanks satisfy safety requirements, extensive quality testing is carried out after assembly, including pressure cycling and burst tests.
The work in this paper stressed that the uniqueness and contribution of this study lie in its actual implementation within a full 0.5 kW pilot-scale green hydrogen generation system rather than only in giving a thorough Electrolyzer design. The system integration strategy, component selection and sizing, operating methodology, experimental validation under actual operating conditions.
The main contributions of the paper are : (1) the development of an integrated automation and monitoring architecture that permits real-time process control, data acquisition, and operational supervision; (2) the full engineering design and experimental validation of a 0.5 kW pilot-scale alkaline Electrolyzer system under realistic operating conditions; (3) a thorough experimental assessment of the system, including electrical performance, hydrogen production rate, and overall system efficiency under various operating conditions; and (4) the conversion of laboratory concepts into a scalable pilot-scale platform that can function as a basis for future hydrogen production systems powered by renewable energy. We have also extended the comparison with previous relevant works to better elucidate the scientific contribution, emphasizing the ways in which the suggested system varies with respect to scale, system architecture, experimental validation, control implementation, and practical operation.
The research and implementation of Electrolyzers and hydrogen storage tanks continue to face obstacles despite notable progress. Cost, scalability, and efficiency at high current densities are obstacles that Electrolyzers must overcome. Like this, storage tanks must strike a compromise between cost, safety, and storage density; both cryogenic and pressurized systems have drawbacks21. Materials science developments, such the creation of new catalysts for Electrolyzers and lightweight composites for tanks, show promise in resolving these issues. A route to more effective hydrogen systems may potentially be provided by hybrid storage systems, which combine the advantages of cryogenic and compressed technology22.
Alkaline Electrolyzers were selected in this work because they are mature and commercially proven technology, offering high reliability, relatively low capital cost, and long operational lifetime compared with other Electrolyzer technologies. They also employ non-precious metal electrodes and an inexpensive alkaline electrolyte, making them particularly suitable for pilot-scale and cost-sensitive applications23.
