List some examples of cargo ships powered by green fuels that are presently in operation. Not small prototype ships, but green fuel powered ships comparable in capacity to the NS Savannah and other nuclear powered civilian ships: https://en.m.wikipedia.org/wiki/Nuclear_marine_propulsion#Ci...
https://www.marinelink.com/news/maersks-first-teu-methanolfu...
And all the ships they've ordered since 2021 can run on methanol:
https://www.maersk.com/news/articles/2023/12/07/maersk-to-de...