Storage, transport and distribution of hydrogen

Hydrogen storage, transport and distribution systems are essential to guarantee supply to potential end users.

Storage

There are various hydrogen storage systems. The choice of the most appropriate system will depend on the final application in which it will be used. In summary, we can cite the following:

Storage under pressure: Normally it is stored at a pressure between 200-350 bar in steel tanks or cylinders. Since the amount of hydrogen stored depends on the pressure -the higher the pressure, the more hydrogen gas is stored-, nowadays work is being done on the development of materials, such as carbon fiber or aluminum, that have the capacity to withstand a pressure of up to 700 bar. This aspect is especially important for the application in transport.

Liquid storage: Hydrogen becomes liquid at a temperature below -235ºC. Special ("cryogenic") tanks are used, which need to be cooled to maintain the required low interior temperatures. This system is only used when you need to maximize storage capacity in a reduced space (for example, in some transport applications).

Metal hydrides: Various metals form compounds with hydrogen, known as hydrides. The formation of these compounds is reversible, so it is possible to easily return to having the initial hydrogen and metal. This system offers a high storage capacity and presents various safety and handling advantages (solid storage under pressure and room temperature) compared to other systems. Its main disadvantages are the heavy weight of the equipment and its high price.

Carbon nanotubes: They are graphite structures, in the form of carbon hexagons, which are arranged to form very small diameter tubes (nanotubes), within which a large amount of hydrogen can be stored. Researchers are developing various procedures and, although there are still disparities in the results, all agree on the great potential of the system.

Transport

In principle, hydrogen can be transported in a gaseous (pressurized) or liquid (cryogenic) state, and can be distributed through pipelines or by trucks, ships or trains, which incorporate any of the storage methods seen previously.

Distribution

Distribution is the process of making hydrogen available to the end user. Currently, it is done from pressure tanks at the point of supply. In the future, when the use of hydrogen becomes widespread in the so-called "hydrogen society", interconnection systems will be designed by pipes that will deliver it to homes (similar to current natural gas connections), and also service stations. of hydrogen -"hydrogenerators"-, which will allow a rapid recharging of any hydrogen-powered vehicle. To this day, there are many projects that have advanced these solutions. By way of example, in 2004 there were already more than 80 hydrogen service stations around the world.