Carbon Conversion Factors for Marine Fuels
The MARPOL Cf values, how they turn specific fuel consumption into CO2 per kilowatt hour, and where they enter EEDI, EEXI and CII.
The carbon conversion factor Cf converts a mass of fuel consumed into a mass of carbon dioxide emitted, based on the fuel’s carbon content. It is the constant that connects a ship’s fuel figures to every carbon instrument that applies to it.
The authoritative table is not in MARPOL Annex VI itself. Resolution MEPC.352(78) points to the EEDI calculation guidelines, and the current amended text is resolution MEPC.364(79), whose paragraph 2.2.1 table gives 3.206 tonnes of carbon dioxide per tonne of fuel for diesel and gas oil, 3.151 for light fuel oil, 3.114 for heavy fuel oil, 2.750 for LNG and 1.375 for methanol, among others.
The article will work the factors through to the figures an engineer actually needs, including carbon dioxide per kilowatt hour of generator output from a stated specific fuel oil consumption, and will show where Cf enters the attained EEDI, the attained EEXI and the CII calculation. It will also flag the common error of quoting a specific fuel oil consumption figure as though it were an emission factor.