REVISTA DYNA ENERGÍA

However, the steps to be taken for its actual use are still quite uncertain, even without taking into account the economic and safety aspects, but only the technological aspects, especially for all the operations of storage, distribution and delivery to the points of consumption. Today, components made of "composite" materials and different types of steel are used, depending on the conditions of temperature, pressure, etc. It is known that some types of steel are sensitive to hydrogen embrittlement which causes them to lose mechanical properties and, eventually, uncontrolled cracking. Depending on the element, it can be oversized or surface coatings can be applied, although the conversion into hydrides or their adsorption by specific materials such as metal sponges, carbon nanotubes or MOFs (metal-organic networks) has also been studied.
However, apart from the laboratory topics, in a more pragmatic field, the use of hydrogen carrier products has been gaining ground, so that hydrogen produced from renewable sources can be transported using the usual methods and used at the points of application, either directly or by releasing the hydrogen by simple means, albeit with a reduction in yield. Two products are most frequently proposed, ammonia (NH3) and formic acid (CO2H2).
Ammonia (NH3) has been at the forefront of proposals to facilitate the use of hydrogen for several years, especially in cases of high energy needs (ships, large boilers, etc.). We already reported on it months ago in these NEWS (https://www.revistadyna.com/noticias-de-ingenieria/el-amoniaco-puede-jugar-un-importante-papel-en-uso-del-hidrogeno), given its ease of manufacture using green hydrogen, the simplicity and low danger of storage and transport and the possibility of recovering this hydrogen without emissions with cracking reactors, or of making it combust directly by means of appropriate mixtures, as its ignition point is at 650º. Only the creation of NOX during combustion should be avoided.
The use of formic acid (CO2H2) is less developed. It has as many or more advantages as ammonia in the "green" manufacturing, storage and transport stages, but its cracking for hydrogen reuse requires complex catalysts. A paper recently published in the Journal of Materials Chemistry A. (3D-printed palladium/activated carbon-based catalysts for the dehydrogenation of formic acid as a hydrogen Carrier) by researchers from CSIC and the Autonomous University of Madrid, seems to be an initial step in the search for a solution. The problem of CO2 emissions in this operation remains, although it seems that its capture and reuse would be feasible.
As can be seen, there is still a long way to go in terms of research and experience before we can do with hydrogen what is expected of it.