IMO Annex VI Regulations and ESI Baselines
Nitrogen oxides
MARPOL Annex VI limits the NO_{X} emissions of future marine engines. The figure below depicts the emission limits for current and future Tiers. The limit value depends on the rated engine speed above 130 rpm.
Figure: IMO Annex VI NO_{X} Limit Value (g/kWh)
As from 1 January 2011 new engines are required to comply with Tier II values for NO_{X}; however, for the purpose of calculating the ESI NO_{X} score the ESI Working Group has decided to maintain the Tier I levels as a baseline for the next few years.
n | < 130 | 130 ≤ n < 2 000 | ≥ 2 000 | RPM |
Limit Value | 17 | 45*n^-0.2 | 9.8 | g/kWh |
Sulphur oxides
In the coming years the lower limits for fuel sulphur content from the revised Annex VI to the MARPOL Convention will come into effect, as shown in the Table below.
Table : MARPOL Annex VI Sulphur Limit % (m/m) in Fuel
Date | High Sea (HFO) | SO_{X} ECA (MDO/Gasoil) | |
2012 | 3.50 | 1.00 | % S (m/m) |
2015 | 0.10 | % S (m/m) | |
2020* | 0.50 | % S (m/m) | |
* Alternative date is 2025, on basis of 2018 review |
The baselines for ESI SO_{X} are in line with the limit values set by IMO and that determined by the ESI working group. IMO limit values are in place for fuels that would normally be used at the High Seas and in (S)ECA’s and these will be tightened in accordance with IMO regulations. In addition there is a second baseline for MDO/Gasoil set by the ESI Working Group at 0.5 % sulphur which will be maintained for the next few years.
The limit value of the sulphur content for fuel used at the High Seas (HFO) changed to 3.50 % (m/m) on 1 January 2012; the limit value for fuel used in SO_{X}-ECA (MDO/Gasoil) changes to 0.10 % (m/m) on 1 January 2015.
Consequently the base line for calculation of ESI SO_{X} of HFO is now at 3.50 % and is used for calculation of ESI SO_{X} scores for bunker operations from 1 January 2012. The base line change for MDO/Gasoil will be applied as from 1 January 2015.
Abatement technologies:
In the case of NO_{X} emissions, it should be noted that where IMO approved abatement technologies of primary or secondary nature are applied, their effects have been included in the respective EIAPP certificate(s) issued.
For ESI SO_{X} the equivalent values for an IMO approved exhaust gas cleaning system may be used for calculation purposes.