This is a pretty broad question. Are you asking which databases might include ammonia production and its subsequent combustion in a marine engine? I'd guess most paid databases will have ammonia production. I doubt however that anyone will have ammonia combustion processes in marine engines. This will require you to research what those combustion emissions will be, paying attention to NOx and N2O formation among possibly others. You might have better luck asking a community more focused on broader LCA questions.
