# A Comprehensive Literature Review on Hydrogen Tanks: Storage, Safety, and Structural Integrity
## 3 Historical Perspective
### Late 20 th Century  
The late 20 th century saw a concerted effort to address the technical challenges hindering the widespread adoption of hydrogen as an energy carrier [49]. During this period, researchers and engineers explored a diverse array of storage technologies, aiming to improve storage capacities, safety, and cost-effectiveness [22; 84].  
One of the principal areas of focus during the late 20 th century was the development of advanced metal hydride storage systems [92]. Metal hydrides offer the potential for high hydrogen storage densities and reversible hydrogen absorption and desorption characteristics [93]. Researchers investigated various metal hydride compositions, including complex hydrides and intermetallic compounds, with the objective of optimizing hydrogen storage performance [94; 95; 96]. Significant progress has been made in enhancing the hydrogen absorption kinetics and stability of metal hydride materials, paving the way for their integration into practical storage systems. This has been achieved by developing new materials and improved synthesis techniques, as evidenced by the work of [PERSON] et al. [82] and [PERSON] et al. [97].  
In parallel, advancements in hydrogen compression technologies played a crucial role in expanding the range of viable storage options [92]. High-pressure hydrogen storage tanks became increasingly prevalent, offering a compact and efficient means of storing compressed hydrogen gas [98]. Innovations in compressor design, materials, and control systems enabled the development of lightweight and durable compression units capable of safely storing hydrogen at pressures exceeding 700 bar [99; 100; 98]. These advancements were instrumental in supporting the deployment of hydrogen refueling infrastructure for fuel cell vehicles and stationary power applications [101; 102; 103]. Furthermore, collaborative initiatives between government agencies, research institutions, and industry stakeholders, such as the Hydrogen Program launched by the United States Department of Energy (DOE) in the late 1970s [63], spurred advancements in compressed hydrogen storage technologies, fostering the commercialization of hydrogen-powered vehicles and stationary energy storage systems [104; 105].  
Moreover, the advent of nanotechnology in the late 20 th century revolutionized hydrogen storage research, offering new avenues for enhancing storage capacities and kinetics. Scientists explored the use of nanomaterials, such as carbon nanotubes, Metal-Organic Frameworks (MOFs), and nanoporous materials, for hydrogen adsorption and storage applications [106; 107]. The high surface area and tunable properties of nanomaterials provided unprecedented opportunities for designing lightweight and high-capacity hydrogen storage systems, driving innovation in both academia and industry [108].  
Additionally, the late 20 th century saw significant efforts to enhance the safety and reliability of hydrogen storage systems. Research initiatives focused on mitigating risks associated with hydrogen handling, storage, and transportation, including developing safety standards and guidelines for hydrogen storage facilities and infrastructure [109]. Collaborative endeavors between government agencies, research institutions, and industry stakeholders facilitated knowledge sharing and technology transfer, accelerating the maturation of hydrogen storage technologies [110].  
Overall, the late 20 th century represented a period of intensive research and development in hydrogen tank storage, driven by the growing recognition of hydrogen as a clean and versatile energy carrier. The advancements during this period established a foundation for the continued evolution of hydrogen storage technologies in the 21 st century, paving the way for the transition toward a hydrogen-based economy.