The Seward Phoenix Log - News of the Eastern Kenai Peninsula since 1966

Report shows air pollutants reduced in Sound


The Prince William Sound Regional Citizens’ Advisory Council recently commissioned a study to quantify how much less air pollution is emitted from tanker ships due to the use of low sulfur fuel. The study, by Starcrest Consulting Group, LLC, evaluated the air pollution from tankers, traveling through Prince William Sound during 2014, by estimating the amount of emissions that would have been released if the tankers had been using fuel with a sulfur content of 2.7, 1.0, or 0.1 percent.

The study found that nitrogen oxide emissions are somewhat reduced, but both particulate matter and sulfur dioxide emissions are substantially reduced. By using 0.1 percent sulfur fuel, tankers in the Sound reduced emissions by approximately 426 tons of sulfur dioxide, 33 tons of particulate matter, and 29 tons of nitrogen oxides annually compared to using 2.7 percent sulfur fuel. Those changes represent a 96 percent reduction in sulfur dioxide, an 80 percent reduction in particulate matter, and a 6 percent reduction in nitrogen oxides each year. A reduction of 33 tons of particulate matter is the equivalent to the emissions from about 5,000 heavy-duty diesel trucks operating for a year, while a reduction of 426 tons of sulfur dioxide would be equal to the annual emissions from approximately 444,000 heavy-duty diesel trucks.

The reductions in tanker air pollution in Prince William Sound are attributable to regulations, developed by the International Maritime Organization, that target three air pollutants: nitrogen oxides, particulate matter, and sulfur dioxide, according to a PWSRCAC press release. These pollutants are produced by internal combustion engines and released in a vessel’s exhaust. To limit the substances, the regulations mandate that large ships either use technologies such as exhaust scrubbers or cleaner fuel to reduce emissions. The tankers in Prince William Sound are complying by burning fuel with a low sulfur content.

As of August 2012, large ships are required to use fuel with a sulfur content of 1.0 percent or less if they operating within the North American Emissions Control Area. The area extends approximately 200 miles offshore of the United States and includes Prince William Sound. In January 2015, International Maritime Organization regulations require vessels in the emissions control area to burn even cleaner fuel, with a sulfur content of 0.1 percent or less. Comparatively, tankers in international waters, more than 200 miles offshore, are allowed to burn fuel with a sulfur content of up to 3.5 percent. Low sulfur fuel is about 60 percent more costly than traditional fuels.

Air quality in Prince William Sound is better today because international regulations have resulted in crude oil tankers emitting far less air pollution than they were just a few years ago, according to the press release. The study did not quantify the potential positive impacts of these reduced emissions on human and environmental health or measure impacts to local air quality. However, reductions in nitrogen oxides, particulate matter, and sulfur dioxide emissions from tanker ships should improve local air quality by greatly reducing the mass of pollutants released in the region each year.

A full report on the tanker air emissions study is available through the council’s website at


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