The IMO’s Marine Environmental Protection Committee (MEPC) met at its 57th session from 1 March to 4 April 2008. During the session, both the revised Annex VI of MARPOL and the revised NOx Technical Code were approved, with the intention to adopt the two at the 58th MEPC session, scheduled to take place in October 2008. The annex and the code are then expected to enter into force in Feb/Mar 2010.
The new revision substantially tightens the NOx and Sulphur limits compared to the existing annex, and also includes requirements governing NOx emissions from ships constructed from 1 January 1990 to 1 January 2000.
New NOx limits :
The revised NOx regulations contain a 3-tier approach as follows:
Tier I (identical to today’s limits) :-
For diesel engines installed on ships constructed from 1 January 2000 to 1 January 2011, the allowable NOx emissions are:
-17.0g/kWh when n is less than 130 rpm
-45.0*n(-0.2) g/kWh when n is 130 rpm or more but less than 2000 rpm
-9.8 g/kWh when n is 2000 rpm or more
Tier II :-
For diesel engines installed on ships constructed on or after 1 January 2011, the allowable NOx emissions are:
-14.4g/kWh when n is less than 130 rpm
-44.0*n(-0.23) g/kWh when n is 130 rpm or more but less than 2000 rpm
-7.7 g/kWh when n is 2000 rpm or more
Tier III :-
Ships constructed on or after 1 January 2016 will have additional limitations when operating in an Emission Control Area (ECA). No ECAs have yet been designated for NOx emissions, but it is expected that both the Baltic Sea and North Sea will be designated as NOx ECAs well ahead of 1 January 2016.
For Tier III ships operating in the NOx ECAs, the allowable NOx emissions are:
- 3.4g/kWh when n is less than 130 rpm
- 9.0*n(-0.2) g/kWh when n is 130 rpm or more but less than 2000 rpm
- 2.0 g/kWh when n is 2000 rpm or more
It should be noted that the Tier III limits cannot be achieved without additional means, such as Selective Catalytic Reduction (SCR) and Water Injection.
NOx Emission Limits for Engines Installed on Ships Constructed Prior to 1 January 2000
Ships constructed on or after 1 January 1990 but prior to 1 January 2000 will be required to comply with the NOx emission limits in force today (Tier I). However, the requirement has been narrowed down to apply to engines with a power output of more than 5000 kW and a per cylinder displacement of 90 litres or above. Moreover, compliance is only required if an Approved Method for obtaining the necessary NOx reduction is available for the engine(s) in question. The regulations also contain a mechanism to ensure that an Approved Method meets a cost-effectiveness criterion which will set a maximum cost for purchasing and installing a method.
Necessary engine adjustments or the fitting of NOx-reducing kits must take place no later than the first renewal survey that occurs 12 months or more after approval of an applicable method. However, if the supplier of an Approved Method is not able to deliver this at the time of this renewal survey, installation may take place at the next annual survey. Detailed requirements for the approval of NOx-reducing methods have been included in the revised NOx Technical Code.
New Limits for Sulphur Content in
The new limits for sulphur content in fuel oil will be:
3.50% from 1 January 2012
0.50% from 1 January 2020
In SECAs :-
1.00% from 1 March 2010
0.10% from 1 January 2015
Sulphur scrubbing will still be an acceptable method for compliance and there will be no HFO ban.
In order to confirm that the refinery industry can meet the demand for low sulphur fuels by 2020, a review clause has been introduced scheduling a fuel availability review to be completed by 2018. If this review reveals that it is impossible to meet the 0.50% limit by 2020, the requirement will be postponed until 1 January 2025.
Marine Exhaust Emission