Hydrogen is the least dense gas known in the world, making it highly susceptible to leakage during storage and transportation. This characteristic is generally safer in open spaces, but if escape is obstructed, the accumulation of large amounts of hydrogen can cause asphyxiation. Furthermore, at certain concentrations, it can ignite and even explode upon contact with fire. Therefore, storage and transportation present significant safety challenges. Currently, high-pressure hydrogen storage technology is widely used by domestic companies, such as Furuit Special Equipment, Zhejiang Juhua, Beijing Keteike, and China Hydrogen.
The table lists some relevant domestic companies adopting the high-pressure hydrogen storage approach.
The hydrogen refueling process in high-pressure hydrogen storage involves the exchange of matter and energy between the hydrogen storage source and the user unit, allowing a large amount of high-energy gas to enter the gas cylinder. Based on different production and usage applications, high-pressure hydrogen storage equipment can be broadly classified into three types: vehicle-mounted high-pressure hydrogen storage containers, high-pressure hydrogen transport equipment, and stationary high-pressure hydrogen storage equipment.
Regardless of the type of equipment used for hydrogen storage, there are two main risks:
1. Stress Risk
(1) High-pressure hydrogen storage and transportation equipment is generally used at tens of MPa and stores a large amount of energy. Due to overheating, overfilling, or other reasons, the equipment may be insufficient in strength and cause an overpressure explosion;
(2) Vehicle hydrogen storage containers and high-pressure hydrogen transportation equipment require frequent refilling. Not only may existing crack-like defects expand, but new cracks may also emerge during use, leading to fatigue failure.
2. Filling risks
(1) When high-pressure hydrogen storage and transportation equipment is filled with gas, the gas medium releases a large amount of heat when the pressure decreases. Through the heat transfer process, the temperature of each connection part of the equipment rises;
(2) Excessive temperature may harm personnel filling the gas chamber, and it also alters the constitutive relationship of the pressure-bearing materials of the equipment, affecting its pressure-bearing capacity;
(3) When hydrogen is pumped or compressed, or during maintenance or hot work, hydrogen may mix with oxygen or other combustion-supporting gases for various reasons. When the concentration reaches a certain limit, it may cause an explosion when it comes into contact with an ignition source.
(4) In addition to the safety risks associated with high-pressure hydrogen storage, other hydrogen storage methods also have some problems, such as: physical hydrogen storage, which includes high-pressure hydrogen storage, has the worst safety and requires high-quality storage tank materials;
(5) Chemical hydrogen storage achieves hydrogen storage by generating stable compounds. Although it is relatively safe, it is difficult to release hydrogen and it is difficult to obtain hydrogen with high purity. Solid hydrogen storage can avoid the problem of low safety of physical hydrogen storage to a certain extent, but it also has other problems such as difficulty in releasing hydrogen and low hydrogen storage density.
Based on the above issues, the following measures are recommended to address the safety concerns related to hydrogen storage and transportation:
1. Accelerate the research and development of new types of storage tanks that are lightweight, pressure-resistant, have high hydrogen storage density, and high safety;
2. To improve the relevant hydrogen storage mechanisms in chemical hydrogen storage technology, in order to find theoretical methods to increase hydrogen storage density, reduce the difficulty of hydrogen release, and increase hydrogen concentration;
By combining hydrogen energy utilization processes and conditions, highly efficient catalysts can be synthesized and supporting hydrogen storage technologies optimized to comprehensively improve the utilization efficiency of hydrogen energy.
3. Improve the efficiency of various hydrogen storage technologies, reduce the cost of hydrogen storage, enhance safety, reduce energy consumption, extend service life, and explore methods that balance the needs of safety, high hydrogen storage density, low cost, and low energy consumption;
4. Research and development of composite hydrogen storage technologies, integrating the advantages of various hydrogen storage technologies and employing two or more technologies in combination. Exploring the combination mechanism of composite hydrogen storage technologies to improve their efficiency.
