MnrAq

Inventories of emissions of GHGs and other relevant substances 105
CO 2 baseline
The carbon content of each fuel type is constant and is not affected by engine type, duty cycle or other
parameters when looking on the basis of kg CO 2 per tonne fuel. The fuel-based CO 2 emissions factors for
main and auxiliary engines at slow, medium and high speeds are based on MEPC 63/23, annex 8, and include:
HFo
MDO/mgo
lng
eF baseline CO 2 = 3,114 kg CO 2 /tonne fuel
eF baseline CO 2 = 3,206 kg CO 2 /tonne fuel
eF baseline CO 2 = 2,750 kg CO 2 /tonne fuel
It should be noted that CO 2 emissions are also unaffected by the sulphur content of the fuel burned. For further
information on specific emissions factors and references, see Annex 6.
NO x baseline
The NO x emissions factors for main and auxiliary engines rated at slow, medium and high speeds were
assigned according to the IMO NO x emission Tiers I and II standards as defined in MARPOL Annex VI,
regulation 13. Emissions for Tier 0 engines (constructed before 2000) were modelled in accordance with
Starcrest (2013). The SFOC corresponding to the energy-based emissions factors was used to convert to
fuel-based emissions factors. NO x EF baseline for boilers (denoted by STM in Table 41) remains the same, as
there are no IMO emissions standards that apply to boiler emissions. The emissions factors used in the study
are presented in Table 41.
Table 41 – NO x baseline emissions factors
IMO Tier Eng speed/type Fuel type SFOC ME/Aux ME EF baseline
(kg/tonne fuel)
0 SSD
MSD
HSD
1 SSD
MSD
HSD
2 SSD
MSD
HSD
HFO
HFO
HFO
HFO
HFO
HFO
HFO
HFO
MDO
195/na
215/227
na/227
195/na
215/227
na/227
195/na
215/227
na/227
92.82
65.12
na
87.18
60.47
na
78.46
52.09
na
Aux eng EF baseline
(kg/tonne fuel)
na
64.76
51.10
na
57.27
45.81
na
49.34
36.12
Reference
ENTEC, 2002
ENTEC, 2002
ENTEC, 2002
IMO Tier I
IMO Tier I
IMO Tier I
IMO Tier II
IMO Tier II
IMO Tier II
all Otto LNG 166 7.83 7.83 Kristensen, 2012
na GT HFO 305 20.00 na IVL, 2004
na STM HFO 305 6.89 na IVL, 2004
Notes: GT – gas turbine; STM – steam boiler
Fuel consumption efficency improvements associated with Tier I and II engines is taken into account and
further explained in the SFOC variability with load section below.
It should be noted that NO x emissions are not affected by fuel sulphur content but do change slightly between
HFO and distillate fuels. For further information on specific emissions factors, FCFs and references, see Annex 6.
SO x baseline
For all three ship emissions sources, SO x emissions are directly linked to the sulphur content of the fuel
consumed. For emission estimating purposes, the typical fuel types (based on ISO 8217 definitions) include:
• heavy fuel oil (HFO)/intermediate fuel oil (IFO);
• marine diesel oil (MDO)/marine gas oil (MGO);
• liquefied natural gas (LNG).
The SO x EF baseline factors are based on the percentage sulphur content of the fuel, with 97.54% of the fuel
sulphur fraction converted to SO x (IVL 2004), while the remaining fraction is emitted as a PM sulphate
component. Therefore, SO x and PM emissions are directly tied to the sulphur content of the fuel consumed.