As a subject matter expert in the field of energy storage, I've spent considerable time researching the intricacies of hydrogen storage. Hydrogen is indeed a challenging substance to store effectively due to its unique properties. It is the lightest element, with a molecular weight of approximately 2.016 g/mol, which contributes to its low volumetric energy density. This low density means that a large volume of hydrogen is required to store a significant amount of energy, which presents a considerable logistical challenge.

The volumetric energy density of hydrogen is a critical factor in assessing its storage feasibility. Compared to traditional fuels like natural gas and gasoline, hydrogen's energy content per unit volume is significantly lower. For instance, natural gas has about 3.2 times the energy density of hydrogen, and gasoline boasts an impressive 2700 times more energy density. This disparity underscores the need for innovative storage solutions to make hydrogen a viable energy carrier.

There are several methods to store hydrogen, each with its advantages and disadvantages.
Compression is one common method, where hydrogen gas is pressurized to reduce its volume. However, the pressure required can be quite high, typically around 350 to 700 bar, which necessitates the use of strong, heavy, and expensive containment systems. This method also results in a relatively small amount of hydrogen being stored per unit volume.

Liquefaction is another approach, where hydrogen is cooled to extremely low temperatures, around -253 degrees Celsius, to convert it into a liquid. This process significantly increases the energy density, but it requires substantial energy input for cooling and maintaining such low temperatures. Additionally, the insulation and containment systems for liquid hydrogen must be highly specialized to prevent boil-off and maintain the cryogenic conditions.

A third method involves chemical combination, where hydrogen is bound to other elements or compounds, effectively storing it in a more energy-dense form. This can be achieved through chemical reactions with materials such as metal hydrides or in the form of hydrogen-rich compounds like ammonia or methanol. While this method can offer higher energy density and potentially lower storage pressures, it introduces the complexity of chemical handling and the energy required for the release of hydrogen during end-use.

Each of these methods has its own set of challenges, including safety concerns, energy efficiency, and cost. The development of safe, efficient, and cost-effective hydrogen storage technologies is a significant area of research and innovation. Advances in materials science, nanotechnology, and chemical engineering are all contributing to the development of new storage methods that could potentially overcome the current limitations.

In conclusion, while hydrogen storage is indeed difficult due to its low volumetric energy density and the complexities associated with compression, liquefaction, and chemical combination, ongoing research and technological advancements are paving the way for more practical and efficient solutions. The future of hydrogen as an energy carrier hinges on our ability to address these storage challenges effectively.

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Hydrogen is difficult to store because has very low volumetric energy density. It is the simplest and lightest element--it's lighter than helium. Hydrogen is 3.2 times less energy dense than natural gas and 2700 times less energy dense than gasoline. ... Hydrogen can be compressed, liquefied, or chemically combined.read more >>