Well to increase safety one can use a fuel like ~methanol with a regular ICE, no need for electric conversion or reformation, just a new carburetor! i was suggesting NH3 because it is much more dense and involves NO carbon at all. Like i said farmers regularly deal with NH3 ... so it can be safely handled.
~methanol Renewable CO2 recycling and synthetic fuel production in a marine environment https://www.pnas.org/content/early/2019/05/28/1902335116