In anything more than small volumes in either very strong, ( or expendable) containers you must keep the H2 and O2 separate until you want them to burn.  Given we have O2 in the atmosphere, it is easier to vent the oxygen and just carry the hydrogen, but as it does not liquefy at any sensible combination of pressures and temperature, storage requires high pressures, and is a pain.

It may make sense on days when wind turbines are generating more than we can use to electrolise water for use on calmer days, but it is not easy.
parts of Siemens are looking at it quite seriously though.

In anything more than small volumes in either very strong, ( or expendable) containers you must keep the H2 and O2 separate until you want them to burn.  Given we have O2 in the atmosphere, it is easier to vent the oxygen and just carry the hydrogen, but as it does not liquefy at any sensible combination of pressures and temperature, storage requires high pressures, and is a pain.

It may make sense on days when wind turbines are generating more than we can use to electrolise water for use on calmer days, but it is not easy.
parts of Siemens are looking at it quite seriously though.