To enable the effective introduction and use of green hydrogen in a sustainable energy network, it essential to have sufficient capacity storage, which in turn drives a need to incorporate different forms and formulations to suit individual demands, due to physical size, safety requirements, geographical location, transportation etc.
Hydrogen is stored in three common phases: solid, liquid and gas. In each state, the cleanliness of the hydrogen is critical to maintain the equipment performance and the hydrogen or fuel purity demanded downstream.
These processes may include the pressurised storage of hydrogen gas at 400, 700 and even 1000 bar, the cryogenic storage of hydrogen as a liquid below 20K (-253°C) or in the formation of a metallic hydride (such as MgH2) all of which is to increase the energy content by volume and to provide a convenient storage or indeed transportation format.
Alternative processes include the use of ammonia, nitric acid, ammonium nitrate and hydrogen peroxide as decarbonised solutions and methanol (preferably as renewable or e-methanol) as a transitional solution which may be considered as convenient options for storage (and indeed transportation) either for the hydrogen itself or in some cases as the primary fuel.
Particulate contamination filtration protects dynamic parts such as pumps, compressors and valves from abrasion damage and control valves and instrumentation to prevent blockage. In these systems the need for contamination protection is upmost given the pressures and / or temperatures involved which will have much finer tolerances on clearance and thus an increased potential for damage. These systems operating at the pressure and temperature extents as they do also generate particulate contamination and therefore filtration is key to preventing the development of a contamination cycle.
Liquid contaminants (oil, water) present in the hydrogen prior to the storage will impact the operation of preparing for the storage as well as the storage itself as it will result in performance and operation interfering with the normal operation. The presence of liquid contaminants in high pressure gas can cause corrosion issues, incorrect monitoring and lead to control delays or loss of responsiveness. The presence of liquid contaminants prior to cryogenic storage will result in frozen particles forming and potentially adversely affecting control equipment and instrumentation by surface and orifice contamination.