An environmental chemist looking into the rush to ban the use of bunker fuel on ships, says the alternatives, especially diesel can be harder to cleanup. Christopher Reddy’s Open Forum piece in the San Francisco Chronicle and is worth a careful read:
“…Bunker oil is highly viscous, sticky, and floats. Bunker oil spills are visually obvious but the very nature of this product allows it to be cleaned up easier than diesel fuel. It can be boomed, skimmed and oil-covered objects along shorelines, often called dirty bathtub rings, can be removed. Diesel fuel is less viscous and harder to contain and recover. Once in the water, diesel insinuates itself into the lifecycles of plants and animals. Toxicity is always difficult to define, but in a relative manner, diesel fuel is significantly more lethal than bunker fuel.
Pure vegetable fuels and biodiesel are attractive alternatives but are not perfect. One marine spill of vegetable oil in Europe left behind a polymerized residue that one scientist argued was more persistent than petroleum fuels. Another spill of vegetable oil in Canada resulted in a large kill of birds. Biodiesel is used to formulate a range of mixtures from B2 (2 percent biodiesel mixed with 98 percent petroleum diesel) to B100 (100 percent biodiesel). While the biocomponent of biodiesel mixtures is much safer and less persistent in the environment, anything less than B100 will contain petroleum diesel with the same negative attributes…”