At this stage it is virtue signalling, as already suggested. Since Rex is allergic to advertising, this might be a ploy for free press coverage.
Currently it costs about US $1.10/kg of Jet A-1, Hydrogen is about $6/kg. H2 has around 300% more energy/kg, so the delta isn’t that big, and solar will only close the gap. Still not seeing how to build cryo tanks (fuel temp circa -275°). Still not understanding how big the fuel cells have to be to make enough electricity to run at cruise, assuming batteries will provide take-off power.
I am all in on the leftie agenda of reducing the carbon footprint. Just not seeing it for aviation, at least not where almost all the Jet A-1 is consumed.