Correct me if I am wrong. My understanding is that hydrogen is an efficient way of getting energy only if it is used as a larger scale storage instead of batteries. Is it?
What hydrogen has going for it is extremely low capex per unit of energy storage capacity, perhaps $1/kWh for a system that stores compressed hydrogen in solution mined salt caverns.
but hydrogen is used to make other things that make it very easy to store as well.
Ammonia is the leading product at the moment.