# A Comprehensive Literature Review on Hydrogen Tanks: Storage, Safety, and Structural Integrity
## 5 Fundamental Issues
### Design Technology of Tanks  
One of the primary challenges in the design of hydrogen storage tanks is achieving the necessary balance between high storage capacity and safety [8]. Since 2014, significant technological advancements have been made in hydrogen storage tanks. Researchers have focused on improving the efficiency, safety, and storage capacity of these tanks, leading to the development of high-pressure composite tanks and the integration of advanced materials like carbon fiber-reinforced polymers. These innovations have allowed for higher hydrogen storage densities and lighter tanks, making them more suitable for various applications, including automotive and aerospace [35; 36]. Despite these advancements, significant challenges remain, such as ensuring the long-term durability and reliability of the tanks under extreme conditions, managing the high costs associated with advanced materials, and addressing safety concerns related to hydrogen's high flammability and potential for leakage. These issues continue to drive ongoing research and development in the field [150; 151]. Innovative design solutions can optimize space while maintaining performance standards [53]. Furthermore, manufacturing these tanks at a scale that meets demand while keeping costs manageable is critical, as advanced materials and manufacturing techniques can be expensive. [PERSON] et al. [135] highlighted the importance of these design considerations in ensuring the safety and effectiveness of hydrogen storage systems. Figure 8: Wordcloud of the most used keywords. When designing hydrogen tanks, it ought to take into account the efficient achievement of the required pressure levels (Section 5.2.1), as well as the need for durability (Section 5.2.2) and effective thermal management (Section 5.2.3). Multistage Metal Hydride Hydrogen Compression (MHHC) systems offer a promising solution for achieving high compression ratios within specified temperature ranges. A numerical study on three-stage MHHC cycles revealed the potential to reach compression ratios of up to 22:1, delivering hydrogen at pressures of 315 bar. This underscores the significance of selecting appropriate materials for each compression stage to optimize compression characteristics, minimize energy consumption, and reduce cycle time. However, achieving these goals necessitates ongoing research into materials with improved compression properties, including fast kinetics, low plateau slope, hysteresis, and adequate heat management strategies. Integrating MHHC systems into hydrogen tank design can enhance overall performance and efficiency while meeting stringent pressure requirements for various applications [137]. [PERSON] et al. [152] proposed an analytical model that integrates the generation of the composite layup and the mechanical evaluation, allowing a rapid and flexible design of the tanks with minimal computational costs. This approach offers a high degree of transparency and ease of implementation, representing a significant advance in designing Type IV hydrogen storage tanks. In more detail, the authors started from the Clairaut equation [153] and focused on geodesic winding paths (Equation (1)). \[\text{cost}=r\sin(\alpha) \tag{1}\]  
where \(r\) and \(\alpha\) are the cylinder radius and the winding angle, respectively. Because the cylinder radius \(r\) does not change on the cylindrical body, the winding angle \(\alpha\) remains constant in this region. However, a rapid variation in the winding angle \(\alpha\) in the dome region is evident due to the radius reduction. Being symmetrical concerning rotation, the dome can be considered a revolution shell, indicating that the shape is obtained by rotating a curve around the central axis. This curve (the meridian) defines the southern direction. While a cylinder has a straight meridian and has only one curvature, the curved nature of the meridian of the dome introduces a second curvature of the shell. The study is based on the Classical Laminate Theory (CLT), which implies that [154; 155; 156]  
\[\left[