
Offshore wind and onshore solar excess can be used to produce hydrogen, not coal.
It takes extra steps and introduces inefficiencies, but it is able to store larger amounts of energy than batteries, and can be used in certain industrial processes which do not run on wires and electrons.
In a succesfully electrified world, it is likely that some ammonia and hydrogen is shipped around the world for such use cases. The main alternative is to keep using fossils.


Yes, as far as I’m able to understand it, ammonia is quite promising for certain industrial purposes (and to run the tankers themselves). Engineer the right engine, and it could potentially run on ammonia while acting as a cracker. Temp store excess hydrogen, and use that for the second part of your journey (or sell it for onshore purposes).