I think that’s only half the truth. Even if we have to convert our entire energy supply, we will still have to import hydrogen, at least in Europe. We have as much sun here as they do in Mordor. So there will be massive shipments of ammonia from the south to us. Forty per cent is therefore probably a little too high
What does hydrogen have to do with the Sun? You can produce the energy necessary for electrolisis from many other sources. Also there was a plan to make a hydroduct from France to Spain to transport green/pink hydrogen.
And the energy used for that electrolysis is enerrgy that can’t be used for something more immediately useful.
There is no such thing as green hydrogen. It’s an energy sink. It’ll always be greener not to generate and use that energy at all.