Storing Liquid Hydrogen at Room Temperature: Alternatives and Technologies

Hydrogen has been recognized as a promising energy carrier for a wide range of applications, from transportation to energy storage. However, one of the significant challenges in handling hydrogen is its storage, particularly in a form suitable for room temperature conditions. In this article, we will explore the challenges of storing liquid hydrogen at room temperature and discuss the available alternatives and technologies.

The Challenges of Storing Liquid Hydrogen at Room Temperature

Hydrogen is unique in its physical behavior, especially when it comes to its liquid state. The critical temperature for hydrogen, below which the liquid phase exists, is -239.95 °C. This means that under normal room temperature conditions (approximately 20-25 °C), hydrogen exists as a gas. Therefore, storing it as a liquid at room temperature is not feasible due to the absence of the liquid phase.

Alternatives to Storing Liquid Hydrogen at Room Temperature

Given the inherent challenges, alternative methods have been developed to store and transport hydrogen effectively. These methods primarily focus on high pressure, adsorption, and chemical bonding:

1. High Pressure Storage

One of the most common methods for storing hydrogen is by compression. High-pressure hydrogen tanks can store hydrogen at pressure levels ranging from 350 to 700 bar. This method is simple and widely used, but it requires robust and expensive storage containers to ensure safety and efficiency.

2. Adsorption Storage

Adsorption is another effective technique for storing hydrogen. In this process, hydrogen is stored on the surface of a solid adsorbent material, such as activated carbon. The surface area of these materials is vast, allowing for a significant amount of hydrogen to be stored. This method can reduce the volume occupied by the hydrogen, making it more efficient for storage and transportation.

3. Covalent Bonding

Hydrogen can also be covalently bonded with other elements to form compounds such as methane (CH4) or lithium hydride (LiH). In these compounds, hydrogen is bound covalently, reducing its reactivity and making it more stable. Additionally, when hydrogen is dissolved in water, it forms hydrogen gas, which can be stored in aqueous solutions.

Historical Context and Current Applications

Back in the 1970s, town gas was a mixture of hydrocarbons, carbon monoxide, and hydrogen. It was generated by the coal gasification process, which involved spraying hot water into coal to produce coke. This gas was stored in large tanks that were actually concentric iron cylinders open at the bottom, floating on water to maintain a seal. As gas was pumped in, the tanks would rise, and as it was used, they would fall.

The same principle can be applied to hydrogen storage generated by electrolyzing water with surplus renewable electricity. When hydrogen is produced, it can be stored in similar large tanks or by using the compression method, ensuring it is ready for use when needed.

Conclusion

While storing hydrogen at room temperature is not feasible, alternative methods such as high-pressure storage, adsorption, and covalent bonding provide viable solutions. These methods have already seen extensive use in various applications, including transportation, energy storage, and industrial processes.

As technology continues to advance, we can expect more innovative and efficient methods for hydrogen storage. The use of high-pressure tanks, adsorbents, and chemical bonding provides a pathway towards a more sustainable and efficient hydrogen economy.