Interim progress report on the revision of MARPOL Annex VI

The IMO's Bulk Liquid and Gases Sub-committee is holding its 12th session (BLG 12) this week in London. One of the most important issues on its agenda is the finalisation of a legal text for the revision of MARPOL Annex VI addressing the reduction of air pollution from ships. As we go to press, BLG 12 is still working on various draft proposals but, pending final agreements on Friday afternoon, the foreseeable suggested amendments might be as follows:


A) Sulphur oxide (SOx) and Particulate Matter (PM) emissions


Particulate Matter (PM) emissions are to be added to the MARPOL Annex VI regulations. However the suggestion is that these are directly linked to the sulphur content of the fuels used by ships.

BLG will probably forward to the IMO's Marine Environment Protection Committee (MEPC) three different alternatives for amending the current regulations on sulphur oxide (SOx) and PM emissions. These three alternatives are:


Alternatives for sulphur cap on fuels used in

Sulphur content


1. Global/all seas







2. Open seas









3. Open seas




 Micro-ECA (max. 24 nm off coast line)











The proposed dates for the application of the various provisions are in brackets to indicate they are indicative and subject to further assessment before final approval.


One important change has been to replace the current Sulphur Control Area (SECA) with a new concept called an Emission Control Area (ECA). The idea is that in these areas, there would be stricter emissions limits for all emissions, not just SOx, but PM and nitrogen oxide (NOx) as well.


In Alternative 1 (global/all seas sulphur cap) the provisions for ECAs and for abatement technologies would become obsolete as from the time the global sulphur cap kicks in (for example 1 January 2012). In other words, compliance will be ensured only through the sulphur content of the fuels used by ships.


Alternative 2 keeps the current system of MARPOL Annex VI with a significant reduction of the sulphur cap for fuels to be used in ECAs.


Alternative 3 introduces a new concept, that of the Micro-ECA. This concept has yet to be clearly define, but in principle it could mean sea areas within 24 nautical miles from the coastal line. In these Micro-ECAs the sulphur content of fuels used by ships would be 0.10%. In addition, Alternative 3 suggests a reduction of the sulphur cap on fuels to be used in open seas to 3.00% and the sulphur cap on fuels to be used in ECAs to 1.00%.

B) Nitrogen Oxide (NOx) emissions

The BLG looks as though it will go for a single suggested limitation on NOx emissions for new engines. These are known as:

-         Tier II limitations for engines installed onboard ships after 1 January 2012. The limitations for Tier II would mean a reduction of NOx emissions from slow speed engines of 15.5% of the current limit (i.e. Tier I limit is 17.0 g/kWh; Tier II limit to be 14.36 g/kWh).

-         Tier III limitations on ships constructed on and after 1 January 2016. The Tier III limitations would mean an 80% reduction from the Tier I NOx limits and they would ONLY be required in ECAs. This needs a clarification: Tier III limitations seem to be linked to the date of ship construction. Therefore, compliance with Tier III would mean that ships constructed on or after 1 January 2016 would have at least a Tier II compliant engine and a piece of abatement technology (most probably Selective Catalytic Reduction (SCR)) which will ensure NOx emission limitations in ECAs.

-         pre-2000 engines - It is not clear whether BLG 12 will agree to suggest amendments to subject engines installed on ships prior to 1 January 2000 to meet Tier I NOx emissions limits. This decision seems to be being left to the MEPC. BLG 12 is discussing some possible ways of upgrading these engines and limiting the requirement to engines installed on ships between 1 January 1990 and 31st December 1999.

Please note this is a preliminary report made before the BLG session has been concluded. A further and more up-to-date report will be given in next week's Weekly NEWS.

Contact: Dragos Rauta