From where does the hydrogen that is used industrially derive?
Most of the hydrogen we use industrially derives from fossil fuels.
And the method used for its production is the so-called steam reforming of hydrocarbons, here methane.......
The carbon monoxide is then removed by the water gas shift reaction:
Here at least the carbon dioxide is not vented to the atmosphere, but its central production (rather than its generation is million of autos by the internal combustion engine) at least allows its storage.
Water is easy.........