2% would make marine fuel about 7% of transport greenhouse gas emissions. BUT marine fuel is insanely dirty. Easily 10X worse than land transport fuels and engi

2% would make marine fuel about 7% of transport greenhouse gas emissions. BUT marine fuel is insanely dirty. Easily 10X worse than land transport fuels and engines, and with no emissions mitigation. It might be simpler to require cleaner marine fuel, but marine fuel is currently a polluter at a large multiple of its share of greenhouse gas emissions. Also, ammonia is a very good candidate for an economically viable energy storage and transport medium for renewable energy generation. Hydrogen is expensive to store and embrittles metal containers and pipelines.