Storage and distribution

There are a number of storage and transportation options for hydrogen.

Once produced hydrogen needs to be stored, used or distributed. When hydrogen is a gas, it is not very dense, which means a small amount takes up a lot of space. The ‘volumetric density’ of hydrogen therefore needs to be increased to allow more to be stored, but this can be costly.

Hydrogen storage

In general, hydrogen can be stored as either a compressed gas, as a liquid, or as a chemical. How hydrogen is stored is dependent on factors such as storage capacity, weight, portability, safety and cost.

Hydrogen gas

Hydrogen gas can be compressed to high pressures and stored in specially designed tanks, like most other gases. The tanks are typically made from strong materials, such as carbon fibre and metal, to withstand pressures of up to 700 times atmospheric pressure. This method is relatively low cost and suited for stationary storage (where there are less space restrictions), and in fuel cell vehicles. For large-scale storage, and for storage for long periods of time, compressed hydrogen can be stored underground in salt caverns or depleted gas fields.

Liquid hydrogen

Hydrogen can also be cooled to a very low temperature (-253 °C) so that it becomes a liquid and is then stored in an insulated cryogenic tank. Liquid hydrogen is more dense than compressed gas and so is often used to store and transport large volumes of hydrogen where space is limited. Liquid hydrogen is commonly used in space shuttles, for example.

Chemical derivatives of hydrogen

Chemical derivatives such as ammonia, methanol and metal hydrides (such as magnesium and titanium hydride) are used to store and transport hydrogen. These methods of storage require a further process of either heating or using chemicals to release the hydrogen for use, which increases its cost.

Transport

Once stored using the technologies described above, hydrogen can be transported using a pipeline or via trucks, rail or ship. Depending on how much and how far the hydrogen needs to go will effect the choice of transportation.

Pipelines can be used to transport compressed hydrogen gas over long distances, and to distribute it within a network, much like natural gas. The pipelines can also be used to store hydrogen until needed. Pipelines are efficient, however the cost of upgrading existing or building new pipelines can be costly.

Trucks can be used to transport hydrogen in special tanks called tube trailers (for compressed hydrogen) or ISO containers (for liquid hydrogen). When hydrogen is a liquid, its higher density makes it better for transporting over longer distances. Compressed hydrogen gas or liquid hydrogen can also be transported by rail, but this is mainly used for industrial applications such as refineries.

Ships can be used to move hydrogen over long distances. This may be in cryogenic tanks, similar to transporting liquefied natural gas (LNG). However shipping hydrogen stored in a carrier such as ammonia or methanol is currently preferred. This is because ammonia, for example, is more easily stored as a liquid at room temperature and relatively low pressure. These chemicals are also commonly shipped in large volumes in existing supply chains and infrastructure which means there are fewer barriers or challenges to moving large quantities of hydrogen this way.

Your task

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