Without additional regulation, burning ammonia in ship engines could cause serious impacts on air quality that could result in more than 600,000 additional premature deaths per year, according to new MIT research.
Technically not green, but I thought you guys would be interested
Batteries don't lend themselves to boats unless they have generators.
Maybe hybrid ships recharging their batteries works but I doubt it.
Electric ships have to have generation somewhere. You'd have to do a lot of work to ruggedize solar panels to handle the travails of the sea. Wind power might help some.
Nuclear power works for US aircraft carriers but it's expensive as hell compared to Bunker fuel and a big ole engine
We're working on fully electrifying our ferries here in Seattle. Plan seems to be limited by current tech, so boats will have some typing up done while loading new cars and passengers on, meaning very high current chargers (kA), which is technically novel so far as I can tell.