The only way that ethanol makes sense is when it is made from cellulose. Using food crops for ethanol will drive up the cost of food. Using a plant that has been genetically selected for high cellulose content and rapid growth would be the way to go.
So far, the process of converting cellulose to ethanol needs more development. It will be soon.
The reason we don't grow our own US sugar cane much anymore (or at all) is because it is very, very labor intensive to harvest. And I'm sure the enviros go whack about the burning off of the leaves and stalks.
OTOH, that is when it's being used for food. It would seem that if being used for its cellulose to make that type of ethanol or biofuel, then maybe none of that has to be done for conversion. Hawaii was once one of the largest growers in the world, wasn't it? They have the highest fossil fuel gasoline costs in the US, too. Maybe there's an opportunity there for them.
On the other hand, there's no substitute for petroleum in aviation fuel - but I don't know about ships - are they run on diesel?