Dave5

Green ammonia is a fuel made through a 100 per cent renewable and zero-carbon processes, such as combining hydrogen from water electrolysis and nitrogen separated from the air through a renewables-powered Haber process. It has been proposed as an alternative fuel source for the shipping industry, although there has long been uncertainty about how and where to invest to create the infrastructure necessary for delivering an efficient, viable fuel supply chain.

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Considering more than 1,000 ports, they found large demand inequality between them. This means that by targeting the largest ports first, a substantial amount of shipping can be decarbonised. 

https://eandt.theiet.org/2024/01/09/green-ammonia-10-ports-could-decarbonise-most-shipping