There's work being done on alternative fuels: https://www.bbc.com/news/business-54511743 https://www.bbc.com/news/business-54511743 Ammonia has no carbon atom

There's work being done on alternative fuels: https://www.bbc.com/news/business-54511743 https://www.bbc.com/news/business-54511743 Ammonia has no carbon atoms in it, just hydrogen and nitrogen which are abundant. It can be synthesized using the Haber process, and electrolysis, all energy inputs can be green. On the con side, its energy density isn't as good as fuel oil (half as energy dense). It needs to be compressed to stay liquid (like LNG). Also it's a poisonous gas. Could be corrosive to certain metals too. Maybe those issues can be worked around though.