MnrAq
MnrAq
MnrAq
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Inventories of emissions of GHGs and other relevant substances 107<br />
The approach taken in this study is compatible with the Second IMO GHG Study 2009, which defined PM as<br />
substances including sulphate, water associated with sulphate ash and organic carbons, measured by dilution<br />
method. Therefore, the model can accommodate changes in fuel sulphur content. This reflects the changes in<br />
PM emissions factors arising from ECAs as defined in MARPOL Annex VI.<br />
For further information on specific emissions factors, FCFs and references, see Annex 6.<br />
CO baseline<br />
Emissions of carbon monoxide (CO) were determined by methods originally described in Sarvi et al. (2008),<br />
Kristensen (2012) and IVL (2004). From these sources, the CO EF baseline factors presented in Table 45 were<br />
used.<br />
Table 45 – CO baseline emissions factors<br />
Eng speed/type Fuel type ME EF baseline (kg/tonne fuel) Aux eng EF baseline (kg/tonne fuel) Reference<br />
SSD<br />
MSD<br />
HSD<br />
HFO<br />
HFO<br />
HFO<br />
2.77<br />
2.51<br />
na<br />
na<br />
2.38<br />
2.38<br />
EPA, 2007<br />
EPA, 2007<br />
EPA, 2007<br />
Otto LNG 7.83 7.83 Kristensen, 2012<br />
GT HFO 0.33 na IVL, 2004<br />
STM HFO 0.66 na IVL, 2004<br />
It should be noted that CO emissions are also unaffected by the sulphur content of the fuel burned and are<br />
the same for HFO and distillates. For further information on specific emissions factors and references, see<br />
Annex 6.<br />
CH 4 baseline<br />
Emissions of methane (CH 4 ) were determined by analysis of test results reported in IVL (2004) and MARINTEK<br />
(2010). Methane emissions factors for diesel-fuelled engines, steam boilers and gas turbines are taken from IVL<br />
(2004), which states that CH 4 emissions are approximately 2% magnitude of VOC. Therefore, the EF baseline is<br />
derived by multiplying the NMVOC EF baseline by 2%. The emissions factor for LNG Otto-cycle engines is 8.5g/<br />
kWh, which is on a par with the data for LNG engines (MARINTEK, 2010 and 2014). However, this value may<br />
be slightly low for older gas-fuelled engines, especially if run on low engine loads, and slightly high for the<br />
latest generation of LNG engines (Wärtsilä, 2011). This emissions factor was used in the bottom-up approach<br />
to determine the amount of methane released to the atmosphere from each of the vessels powered by LNG.<br />
The majority of LNG-powered engines operating during the 2007–2012 time frame are assumed to be Ottocycle;<br />
all LNG engines have been modelled as low-pressure, spark injection Otto-cycle engines, which have<br />
low NO x emissions. From these sources, the CH 4 EF baseline factors presented in Table 46 were used.<br />
Table 46 – CH 4 baseline emissions factors<br />
Eng speed/type Fuel type ME EF baseline (kg/tonne fuel) Aux eng EF baseline (kg/tonne fuel) Reference<br />
SSD<br />
MSD<br />
HSD<br />
HFO<br />
HFO<br />
HFO<br />
0.06<br />
0.05<br />
na<br />
na<br />
0.04<br />
0.04<br />
IVL, 2004<br />
IVL, 2004<br />
IVL, 2004<br />
Otto LNG 51.2 51.2 MARINTEK, 2010<br />
GT HFO 0.01 na IVL, 2004<br />
STM HFO 0.01 na IVL, 2004<br />
It should be noted that CH 4 emissions are also unaffected by the sulphur content of the fuel burned and are<br />
the same for HFO and distillates. For further information on specific emissions factors and references, see<br />
Annex 6.