New regulations mean cleaner air in Prince William Sound

By Austin Love
Council Project Manager

Crude oil tankers in Prince William Sound are using cleaner fuel than they were just a few years ago. New regulations, created by the International Maritime Organization, aim to improve air quality by limiting pollutants emitted from large ships. The regulations target three air pollutants produced by internal combustion engines and released in vessel exhaust: sulfur oxides, particulate matter, and nitrogen oxides.

These pollutants can have a variety of negative impacts on the environment and human health. Sulfur and nitrogen can cause acidification in the environment leading to declines in species abundance and biodiversity of plants and fish. They can cause nutrient enrichment that can lead to excessive algae growth and fish kills in aquatic ecosystems. Human health impacts can include increased risk for lung disease, asthma, autism, and heart disease.

The new regulations mandate that ships use either cleaner fuels or new technologies, such as exhaust scrubbers, to reduce pollution from large marine vessels. The tankers in Prince William Sound are complying by burning fuel with low sulfur content. As of August 2012, ships had to burn fuel with a sulfur content of 1.0 percent or less if they were within the North American Emission Control Area, which extends approximately 200 miles offshore. As of January 1, 2015, vessels within the emission control area had to burn even cleaner fuels, meaning tanker fuel emissions in Prince William Sound now have 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 sulfur content up to 3.5 percent. The new low sulfur fuel is about 60 percent more costly than traditional fuels used to run ships, but using low sulfur fuels can significantly lower engine and fuel systems maintenance costs.

One caveat in the new regulations allows certain types of ships to burn higher sulfur fuel in Prince William Sound and coastal waters until 2020. This exception applies to ships that were built before 2011 and use steam boilers for propulsion power. Only one ship currently calling in Port Valdez, the SeaRiver Sierra, uses this type of propulsion. The Sierra could burn 3.5 percent sulfur fuel and be in compliance; however, the Sierra typically burns cleaner fuel while operating in the Sound, averaging 1.4 percent. This ship is expected to be replaced by a new ship, the SeaRiver Eagle Bay, by the end of 2015. The Eagle Bay will use 0.1 percent or less sulfur fuel while operating in Prince William Sound and coastal waters.

Burning the cleaner fuel will lead to significant pollution reductions in the region. Tankers burning cleaner fuels will likely reduce the amount of these pollutants released into Prince William Sound by hundreds of tons per year. Using U.S. Environmental Protection Agency estimates, nitrogen oxides could be reduced from 340 to 300 tons per year, sulfur oxides from 300 to 11 tons per year, and particulate matter could be reduced from 70 to 9 tons per year. The council has commissioned a study that will more accurately quantify the reductions from tanker’s emissions resulting from the new regulations. Results of that study should be available in the fall of 2015.