MnrAq

288 Third IMO GHG Study 2014
CH 4
Methane emissions result from combustion of heavy fuel oils and distillates and from incomplete emissions of
LNG. The emissions factors are constant over time.
Region
Fuel type
Table 60 – CH 4 emissions factors (g/g fuel)
Year
2012 2030 2050
Global HFO 0.00006 0.00006 0.00006
LSFO 0.00006 0.00006 0.00006
MGO 0.00006 0.00006 0.00006
LNG 0.05 0.05 0.05
N 2 O
Nitrous oxide results from the combustion of fuels. Its emissions factors are constant over time.
Table 61 – N 2 O emissions factors (g/g fuel)
Region
Fuel type
Year
2012 2030 2050
Global HFO 0.00015 0.00015 0.00015
LSFO 0.00015 0.00015 0.00015
MGO 0.00016 0.00016 0.00016
LNG 0.000108 0.000108 0.000108
HFC
Emissions from HFC result from leaks from cooling systems and air conditioners. They do not emerge from
fuel combustion but are assumed to be driven by the number of ships. There are several HFCs with different
GWPs. The most relevant are presented in the following table.
Species GWP Notes
Table 62 – HFCs used on board ships
R-22 1,810 R-22 (chlorodifluoromethane) has been the dominant refrigerant in air conditioners used on
board ships. The production of R-22 has been phased out under the Montreal Protocol in
many countries. We assume that it is used only in vessels built before 2000.
R-134a 1,300 R134a (1,1,1,2-Tetrafluoroethane) is used as a replacement for R-22 in vessels built from 2000
onwards
R-404a 3,700 R404a is a mixture of R125, R143a and R134a. It is used predominantly in fishing vessels but
also in freezing and cooling equipment in other vessels.
Assuming that ships built before 2000 have a 25-year lifetime, R-22 will have become obsolete in shipping
by 2025. We do not model that other HFCs will be phased out, that air conditioner leakage rates will change
or that other coolants will replace HFCs. Under these assumptions, the following emissions per ship are
calculated.