Energy Density -
Hydrogen and fuel cells provide better energy density than any
battery. Even considering efficiency improvements of both technologies,
aircraft fuel cells are expected to be 3-5x more energy-dense.
Safety -
The aerospace industry view is that the safety of hydrogen is
manageable.
Operational -
Hydrogen offers rapid refuelling times which can be accomplished
within aircraft turnaround, unlike battery charging which will take at
least an order of magnitude longer.