# A Comprehensive Literature Review on Hydrogen Tanks: Storage, Safety, and Structural Integrity
## 1 Introduction
### Problem Statement and Formulation of the Research Questions
vehicles such as the Toyota Mirai and Hyundai Nexo [35]. However, several barriers need to be overcome. First, the high cost of hydrogen storage tanks, which are typically constructed from expensive composite materials, remains a significant challenge [24; 30]. Reducing the cost of these tanks while maintaining safety and durability standards is essential for widespread adoption [34]. Moreover, the gravimetric and volumetric energy densities of high-pressure hydrogen tanks are still below that of gasoline and gasoil, leading to shorter driving ranges and larger, heavier tanks compared to traditional fuel systems [34; 36]. This directly affects vehicle design, requiring space optimization and lightweight efforts to ensure that hydrogen vehicles remain competitive in terms of range and performance. In addition to cost and energy density, safety concerns surrounding the storage of hydrogen at such high pressures are critical [37; 38]. Advances in sensor technologies, leak detection systems, and tank materials are crucial for improving safety, but rigorous testing and certification protocols still need to be standardized across markets [39]. Finally, the refueling infrastructure for hydrogen remains underdeveloped, limiting the practical use of Fuel Cells Vehicles (FCVs) in many regions [34; 40]. In aerospace, composite materials, especially Glass Fiber-Reinforced Plastics (GFRP), are crucial for their lightweight and high-temperature resistance [41; 42]. GFRP emerged in the 1960s for military and aerospace uses, and later expanded to civilian markets. By 1990, composite tanks for methane at 250 bar were available, evolving to hydrogen storage systems at 700 bar. Key challenges include management, weight, volume, and thermal behavior. Hydrogen, with its high energy content per weight, is advantageous for small military aircraft and long-duration flights. However, water vapor emissions from hydrogen fuel, a potent greenhouse gas, remain a concern [36]. Hydrogen storage in aerospace uses liquid or gaseous forms. LH\({}_{2}\) is favored for its high energy density, though it requires managing heat losses and safety concerns, illustrated by the modified B-57 bomber and Boeing's Phantom Eye UAV. GH\({}_{2}\) storage involves high-pressure cylinders, but faces challenges like material limits, long refueling times, and improved discharge kinetics [36; 43]. Historical uses in airships and ongoing advancements highlight the evolution and complexity of hydrogen storage in aerospace [38; 42; 44]. The incorporation of composite materials, predominantly fiberglass, has markedly enhanced the performance of many maritime vessels, including motorboats, sailboats, catamarans, yachts, and ferries. These materials enhance speed and resistance while simultaneously reducing weight and fuel consumption. Furthermore, hydrogen is emerging as a promising renewable energy source for the maritime sector. Hydrogen fuel cells, which convert hydrogen into electricity, offer a clean energy alternative for the propulsion and powering of ships and onboard systems, with the sole byproduct being water. Despite the considerable advantages offered by hydrogen fuel cells, including high efficiency and low emissions, the widespread adoption of this technology in the maritime industry is hindered by the lack of infrastructure for the production, transportation, and storage of hydrogen. The storage of significant quantities of hydrogen on ships necessitates implementing robust infrastructure and safety measures. The employment of an array of hydrogen storage techniques, including high-pressure, LH\({}_{2}\), metal alloy, and chemical storage, is of paramount importance for ensuring the safety and stability of maritime vessels. The performance and safety of hydrogen storage tanks are influenced by several factors, including the gaseous characteristics of hydrogen, heat generation during release, and external factors such as the stress load on the ship and environmental conditions.