Glycerol additive makes cruise ships greener


August 23, 2012

A new additive based on glycerol helps reduce pollution in marine bunker fuel used in cruise ships (Photo: Shutterstock)

A new additive based on glycerol helps reduce pollution in marine bunker fuel used in cruise ships (Photo: Shutterstock)

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The bunker fuel used in cruise liners and freighters is some of the cheapest, crudest fuel available. It’s also among the dirtiest. Scientists from the Maine Maritime Academy and SeaChange Group LLC led by George N. Harakas, Ph.D announced at the 244th National Meeting & Exposition of the American Chemical Society that they have developed what they call "Bunker Green" fuel. This fuel uses an ingredient commonly used in food and medicine to reduce sulfur and other emissions in ocean vessels.

People talk about the “bottom of the barrel,” but bunker fuel literally is just that. Thick, viscous and cheap, it’s the dregs of the oil refining process. To the uninitiated, it resembles a sort of runny tar. But it will burn and large, slow-speed diesel engines can manage it. Because of its price, bunker fuel has been standard for large marine engines since the 1950s and is commonly used in freighters, cruise ships, tankers and other large ships.

The problem is that bunker fuel is very dirty. There’s too much sulfur in it and it’s often contaminated with all manner of elements. Air pollution is of particular concern when such ships steam close to shore and enter urban harbors and in recent years, a lot of pressure has come to bear on passing laws to reduce emissions.

Bunker Green is a simple fuel additive for bunker fuel. It’s glycerol, which is a colorless, odorless, the byproduct of soap manufacturing and biodiesel refining. It’s used in medicines, sweeteners, cosmetics and as a filler in low-fat foods. Because glycerol mixes with oil about as well as water does, a surfactant is used to reduce the surface tension of the liquid. Detergents are one example of a surfactant whose addition allows the glycerol to mix with the bunker fuel.

This simple addition has impressive results. According to the team’s report, the additive helps remove the sulfur and reduces soot emissions by 15 percent and nitrogen oxide by 26 percent.

Source: American Chemical Society

About the Author
David Szondy David Szondy is a freelance writer based in Monroe, Washington. An award-winning playwright, he has contributed to Charged and iQ magazine and is the author of the website Tales of Future Past. All articles by David Szondy

Either there is more to it than adding glycerol and a surfactant to the tank while fueling, something strange is happening to the sulfur in the engine, or the sulfur is being deposited in the tank or fuel system. I hope the shipowners know.

I hope this is cheap enough that it get used outside of national waters.


Isn't Glycerol the by-product of bio-diesel? Cruise ships could process their own waste and make it onboard. Or the bio-diesel makers can have good buyers lined up.


Great, as long as there are no increases of other harmful emissions! Where does the sulphur go???


I'm not a chemist, but my theory is that the sulfur is still there in the exhaust. It's just that the addition of glycerol changes it to a somewhat less harmful form. It's sulfate particulate emissions that are the real concern from burning bunker fuel. Sulfur dioxide gas is considered less harmful. So by adding glycerol, you add hydrogen and oxygen to the mixture, creating sulfur dioxide instead of sulfates and hydrogen sulfide, which itself burns to create water and more sulfur dioxide.


I am going to guess that the sulfur is reduced by the addition of Glycerol to the degree that Bunker fuel has been substituted, they don't say what percentage of Glycerol is used or how much the NMPG has been reduced. This is much like adding ethanol to gasoline.


soo, another thing left out is , what is the cost of this glycerol, if it makes the cost increase significantly, unless laws are put into place to require its use, they ship captains will not use it not matter how green it makes the fuel.

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