The international community is concerned about the impact of airborne sulphur and nitrogen emissions especially where high traffic sea lanes meet densely populated areas.
Sulphur is a natural component of liquid fuels. During the combustion process, sulphur oxide (SOx) is generated. This causes acidification and contributes to the formation of particulate matter. Consequently the IMO has imposed emission limit values to be met by shipping fuels worldwide. Moreover the entire Baltic was declared an ecological area (ECA = Emission Control Area) in 2005. One year later, the same was done for the North Sea and subsequently for the entire seaboard around the US and Canada. In ECA’s ships are only allowed to use fuels (low-sulphur distillate fuels) with a sulphur content 90% below that of the average fuel worldwide.
The greatest step up to now? The 0.10% sulphur limit applied in ECA’s. As a result, vessels have to stop using heavy fuel oil (HFO, a secondary product of refining) and adopt more expensive distillate oil fuels with a sulphur content of 0.10% (MGO). In addition to this, as of January 1, 2020, all ships above 400GT need to fuel on board that does not exceed the 0.5% Sulphur limit compared to 3.5%.
Nitrogen oxides (NOx) contribute, among others, to the generation of particulate matter. They result from high temperature combustion, as happens typically in engines. An 80% reduction in NOx emissions compared to the Tier II standard: this is the ambitious goal of the Tier III standard. However, the Tier III standard only applies to newly-built vessels and moreover, it does so exclusively in specially-designated areas (NOx Emission Control Areas or NECA’s). Currently the 200 nm (nm = nautical mile) area around the US seaboard is designated as a NECA. The Baltic Sea (including Russia) and the North Sea will be an NECA from 1 January 2020.