Jon PENNYCOOKI have some concerns about the production of ammonia, especially if it depends on energy from fossil fuels, where they are getting their hydrogen from, and the impact of fuel leaks, but hopefully it's better than what shipping uses currently.
"World’s first ammonia-powered ship runs without oil, targets zero-carbon shipping"
https://interestingengineering.com/innovation/ammonia-powered-ship-hd-hyundai
Jack