# A Comprehensive Literature Review on Hydrogen Tanks: Storage, Safety, and Structural Integrity
## 5 Fundamental Issues
### Design Technology of Tanks
#### 5.2.1 Pressure of Tanks
Finite Element Method (FEM) analysis for stress distribution and numerical simulations for heat transfer, the simulation results demonstrate that it is 31% lighter, has an 11% higher capacity, and is 42% cheaper than conventional Type IV hydrogen storage tanks [150]. Stress analysis indicates that the innermost shell endures the highest Von Mises stress, though it remains within safe limits. Integrating conduction and radiation models, heat transfer analysis demonstrates that Multi-Layer Insulation (MLI) effectively minimizes radiation heat ingress [140], allowing for extended storage without cooling. As highlighted by [PERSON] et al. [161], the design of hydrogen tanks for FCEVs must respect several essential process design requirements, and different leak, permeation, and pressure cycling tests with high-pressure inert gas and hydrogen must be performed to achieve approval to develop the basis of safety. Through Finite Element Analysis (FEA), the structural behavior of tanks under different loading scenarios, including internal pressure, external forces, and thermal effects, can be obtained, and it is possible to improve efficiency and safety through design optimization [53; 150; 162; 163]. Computational Fluid Dynamics (CFD) software is also employed to support the design of the storage tank, enabling numerical investigations to obtain innovative hydrogen storage tanks [164]. [PERSON] et al. [140] focused on the design strategy and heavy-duty track case study of LH\({}_{2}\) fuel tanks. The study addressed structural design, insulation performance (MLI for insulation), and material selection. The study highlighted economic feasibility challenges for larger tanks and recommended expanded regulations and additional standards to optimize design and installation space efficiency. Other studies have been carried out on the use of LH\({}_{2}\). [PERSON] et al. [165] dealt with the advantages and challenges of storing and transporting hydrogen in its liquid form (LH\({}_{2}\)) as opposed to its high-pressure gas form. The use of LH\({}_{2}\), which can be compressed to a volume 800 times smaller than its gaseous state and has roughly ten times the density of high-pressure hydrogen gas (700 bar), offers significant benefits for storage and transportation efficiency [150]. However, maintaining hydrogen in a liquid state requires advanced insulation to keep the temperature at cryogenic levels (20 K) [165]. Optimization of the design of tanks, pressures, and hydrogen forms, mostly in aerospace fields, is still under investigation [150; 44; 166]. Due to the three main storage methods (high-pressure gaseous storage, low-temperature liquid storage, and solid-state storage), each has advantages and disadvantages. Additionally, new technologies are currently being studied. High-pressure gaseous storage offers a high energy density, but it is a costly and safety-risky method due to maintaining a high pressure. While LH\({}_{2}\) storage provides an optimal density, it is inherently volatile and requires significant energy input during production. Solid-state storage, utilizing hydride, offers a high level of security and a high volumetric density, although the gravimetric density is comparatively lower. A promising approach is the high-pressure hybrid storage vessel, which combines gaseous and solid-state methods [167].