A fermentation process discovered in 1914 by Chaim Weizmann can convert waste biomass and fast growing crops into a diesel alternative with an energy density exceeding ethanol.
In the process, acetone, butanol, and ethanol are produced by fermentation of sugars and the result is catalyzed into the final product. The process was used by the British to manufacture explosives during the first world war.
If this fuel does not absorb atmospheric moisture or induce corrosion it could be a partial replacement for marine fuels. Currently, diesel operators looking for a renewable source of fuel are limited to B100 biodiesel or the B80 Bio/Petro blend. Renewable fuels can be a powerful marketing point for tourist vessels which is magnified when the tourist attraction is the natural beauty of the operation area.
The article in the San Fransisco Chronicle mentions the use of low sugar sources of fermentables like woody biomass which were not economically viable in ethanol plants set up for high sugar sources like corn.
The ten year long program is thought to be the closest to commercialization because of high efficiency energy conversion.
Photo: Commercial Maritime Picture Archive