The focus will be put on multi-component AB₂-type intermetallic alloys (A=Ti,Zr; B=Mn,Cr,V,Fe,Ni,…) to be used for both hydrogen storage and compression. These materials combine reasonably high hydrogen storage capacity (~2 wt.%), fast H absorption / desorption kinetics and wide opportunities for the tuning thermodynamics of their reversible interaction with H₂. The price reduction will be achieved by the use of less expensive components (e.g., FerroVanadium instead of pure V) and / or reduction of the content of the expensive ones (e.g. Zr). This strategy is similar to the one for companies involved in the manufacturing of the MH alloys (e.g., GfE/DE). Recently, the UWC team showed additional opportunities of the tuning hydrogen sorption performance (including quantifying of composition – properties relationships) and upscale of the preparation of this kind of the alloys via induction melting. These activities will be further elaborated within WP1 in the course of collaborative activities of IFE, HZG, UWC and ITSN. The optimised materials (incl. improved cycle life and poisoning tolerance) will be manufactured by the UWC team in the amounts necessary for making the prototypes in WP2-WP3.

The focus will be put on intermetallic or solid solution hydrides characterised by high volumetric hydrogen storage density, low hydrogenation / dehydrogenation heat effects, sloping plateaux in the range 5 to 50 bar at room temperature, fast hydrogenation / dehydrogenation kinetics, as well as minimised labour efforts and costs for their industrial-scale production and further processing (e.g., powdering).

Taking into account safety limitations underground (operating pressures must be below 20 bar), these materials have to have higher thermal stabilities corresponding to plateau pressures at the room temperature between 3 and 10-15 bar; high reversible hydrogen storage capacity in the specified pressure range is very important.

MH materials for this application should be also optimised from the kinetic, manufacturability and costs points of view. Thermodynamic performances of these materials should be carefully aligned with the specifications to the refuelling systems, taking into account available heating and cooling temperatures, hydrogen pressure in the customer’s supply pipeline, required hydrogen discharge pressure (e.g. 200 bar for the surface refuelling). If high compression ratios are required and multistage layout of the MH compressor is necessary, special attention should be paid to the alignment of thermodynamic properties of the MH materials belonging to the previous and the next compression stages; the general approach was shown by Norwegian and South African participants. The MH materials should be also characterised by flat plateaux and maximum reversible hydrogen storage capacities at the operating temperatures and H₂ pressures.