The only part of the article I was referring to was the Orkney ferries which use the Hydrogen in an ICE. This is a 2018 introduction to the project. https://hydime.co.uk/
The ferry is now running but can only use the Hydrogen in port until the necessary legislation is put in place.
As regards efficiency, Hydrogen is a more efficient fuel than petrol. However, it depends on how it is mixed in the engine. The theoretical maximum power output from a hydrogen engine depends on the air/fuel ratio and fuel injection method used. The stoichiometric air/fuel ratio for hydrogen is 34:1. At this air/fuel ratio, hydrogen will displace 29% of the combustion chamber leaving only 71% for the air. As a result, the energy content of this mixture will be less than it would be if the fuel were petrol. Since both the carbureted and port injection methods mix the fuel and air prior to it entering the combustion chamber, these systems limit the maximum theoretical power obtainable to approximately 85% of that of petrol engines. For direct injection systems, which mix the fuel with the air after the intake valve has closed (and thus the combustion chamber has 100% air), the maximum output of the engine can be approximately 15% higher than that for petrol engines. Diesel engines are more adaptable to hydrogen than petrol.
The new Norwegian ferries are battery-powered. They are charged while turning round in port.