There are several hydroelectricity sites where water is pumped up to the reservoir during the night only to run back through the generators during the day, when need and rates are higher. Somehow the engineers and business analysts say this is profitable.

In a similar manner, there will be a thermodynamic loss when changing from electricity to hydrogen to electricity. Maybe 25%. Maybe 50%. But the free market allows this, why not?

With hydrogen being stored for the grid, there would be a lot less infrastructure than trying to put hydrogen directly into cars.

Anyways, the experts will figure this all out.