It's not about purity, it's about removing carbon from the atmosphere. All the existing industrial scale hydrogen production gets hydrogen from carbon based fue

It's not about purity, it's about removing carbon from the atmosphere. All the existing industrial scale hydrogen production gets hydrogen from carbon based fuels, using other energy. There doesn't appear to be an option at this time for producing carbon at any reasonable scale without using carbon fuel sources. If we get fusion power, really cheap power, instead of splitting water using that free energy we could just directly run electric cars. There is a cynical pushing of "green hydrogen" from the companies that want to preserve their internal combustion industrial infrastructure (notably Japan), and from carbon fuel producers but calling the result 'green hydrogen'. The issue is there is no clear pathway. When/if that happens, there's still the issue of the infrastructure to manage carrying around hydro to refuel or making it at the source. There's no there there.