The electricity to energize this process will be generated by (wait for it)...
Fossil Fuels!
How about hydroelectric using tidal action. Each tidal cycle creates massive amounts of electricity that can create hydrogen through hydrolysis. Once the electrical energy to hydrogen, you now have an energy storage system.
It doesn’t have to be that way.
Nuclear reactors could produce enough electricity to accommodate.
While they’re at it - they could also power desalination plants that would provide fresh water for agriculture instead of draining aquifers.
But…alas - it makes too much sense.