Just be careful with Hydrogen energy density as there’s a huge range of non obvious issues. Compressed you lose a great deal of energy converting it to kinetic energy and weight due to the containers + engines. Fuel cells also need electric motors and ideally a hybrid battery.

Cryogenic fuel looks great until you need to have it sit around unused. Embrittlement, volume, cost, and a rage of safety hazards make it unappealing for aircraft or ships.

So, my guess is the ideal long term solution barring “super batteries” is some sort of synthetic hydrocarbons that uses atmospheric CO2 but we are a long way from viability there.