Pollutant Air Emissions

Environmental Impact

Most ships are equipped with engines that consume heavy oil, which may have a higher sulphur content that produces sulphur oxides (SOx), nitrogen oxides (NOx) and particulate matter when burned. These pollutants disperse themselves in the atmosphere to contribute to smog and acid rain – forms of pollution that are of particular concern for large ports which handle heavy intermodal activity in an urban setting.

Action Plan Arising from the Environmental Program

Distinct performance indicators have been developed to combat the two main air pollutants emitted by ships; namely sulphur oxides and nitrogen oxides. Other pollutants, such as particulate matter and volatile organic compounds, which are not covered by the MARPOL Convention and for which reduction technologies are less developed, could potentially be integrated into a subsequent phase of the program’s implementation.

Sulphur oxides emissions are directly linked to the sulphur content of the fuel used. Aside from the implementation of practices to reduce fuel consumption, the performance indicator encourages the use of higher quality fuel or of technologies allowing for an equivalent reduction in emissions. However, the scarcity of such fuel, combined with the high prices charged by oil companies, could limit potential gains in the short term.

Nitrogen oxides emissions depend more on engine design than on fuel quality. The criteria proposed by the performance indicator are directly inspired by existing or proposed IMO standards, with a view to advancing implementation of the latter by several years. However, participants who are determined to reduce their nitrogen oxide emissions will have difficult choices to make, given that the majority of technologies that are either in use or available have the side effect of increasing fuel consumption and greenhouse gas emissions.

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