Third IMO Greenhouse Gas Study 2014

250 Third IMO GHG Study 2014
Notes: Base fuel assumption: HFO 2.7% sulphur
SFOCs
To develop fuel-based baseline emissions factors in g pollutant/g fuel or kg pollutant/tonne fuel, the cited
energy-based baseline emissions factor (g pollutant/kWh) needed to be divided by a related SFOC. In general,
energy-based baseline emissions factors and SFOCs were derived from IVL (2004), which analysed ENTEC
(2002). The exceptions to this rule are for LNG-powered engine and diesel-cycle NO x emissions. The LNG
SFOC used for this study was 166 grams of fuel/tonne fuel (Wärtsilä, 2014).
IMO has capped NO x emission rates for Tier I and II engines through regulation and expressed the emission
limits with energy-based emissions factors. Since there is no related SFOC, we used the SFOCs for NO x ,
relating to diesel-cycle main and auxiliary engines, presented in Table 23. It should be noted that for the other
pollutants, baseline emission factor related SFOCs were used to convert to the fuel-based baseline emissions
factors, and that the efficiencies associated with Tier I and II engines is captured by the use of the tier-related
SFOCs when estimating emissions over a given distance and/or time.
Table 23 – IMO Tier I and II SFOC assumptions for NO x baseline emissions factors
Engine type IMO Tier Rated speed SFOC g/kWh
Main I SSD 195
I MSD 215
II SSD 195
II MSD 215
Aux I MSD/HSD 227
II MSD/HSD 227
The baseline emission factor related SFOC to the energy-based baseline emissions factors depends on the
rated speed of the engine, fuel type and if the engine is used for propulsion or auxiliary service. The related
SFOCs associated with the energy-related baseline emissions factors are presented in Table 24.