The question for me would be: is hydrogen really the best chemical for energy storage? (I genuinely do not know actually.) Although you are not explicitely sayi

The question for me would be: is hydrogen really the best chemical for energy storage? (I genuinely do not know actually.) Although you are not explicitely saying that, it seems to me that the underlying assumption behind the hydrogen-as-storage argument is that hydrogen is produced from surplus electricity and then used e.g. in transportation. The choice of hydrogen is then justified because only water is released into the environment in that scenario. However, that seems terribly inefficient to me, if only because you have to move hydrogen around. An efficient storage system should work in a closed loop: you produce hydrogen and oxygen by electrolysis with surplus electricity, store hydrogen locally, and use the locally stored hydrogen to produce electricity when needed. There is no need to release anything into the environment. In particular, other chemicals could be used instead of hydrogen.