At least in trucking, the H power transition has made an official commercial beginning in South Korea.  That's a pretty big step towards demonstrating its feasibility in this area of the transportation energy problem, which is one of the biggest problem areas in making the transition to renewable energy.

The other main important question is how rapidly the production of Green Hydrogen can be scaled up to meet the demand of replacing the Millions of gallons of diesel burned each year to move our food from farm to table and toys from Amazon distribution center to living room entertainment center.  China has gone a long way toward producing the mega quantities of Solar PV panels needed, however they're not all deployed nor are they all hooked up to Hydrolysis plants that can take millions of gallons of water and turn it into millions of gallons of liquid H, which is how it probably will leave the factory as then used to fill compressed gas H tanks at truckstops.  At some point NG pipelines may be converted to carry H instead, but in the beginning I suspect it will mostly be moved in bulk as a liquid.

The FSoA is well behind China in both solar PV total generating capacity as well as in production of green H.  Currently, the cost of H in the FSoA is quadruple what it is coming in at over in Asia, and then even the cheaper Asian price is higher than the cost of diesel.  So inevitably, if this transition moves forward it's going to raise transportation costs until such time as the cost of the H is brought down significantly.

The transition is likely to have many supply-demand imbalances which will also vary by region and country and will depend a lot on how subsidies are sprinkled out and how the financing is done.  That is likely to be a major political football in the energy and transportation industries.

However, despite all the obvious problems, it's a hopium-full break from the usual Star Trek ideas that get floated every day for replacing FFs, the technology all exists and the only question is how much Green H can be produced how fast?  They will need a LOT of it to completely substitute for Diesel in all the trucks driving on the Eisenhower Interstate every day.  How much time they have before there are substantial shortfalls in diesel supply is a known unknown.  The countdown has begun.

https://www.hydrogeninsight.com/transport/commercial-sales-of-hydrogen-engine-trucks-will-begin-this-year-followed-by-exponential-growth-analyst/2-1-1656234

Commercial sales of hydrogen-engine trucks will begin this year, followed by exponential growth: analyst

RE