The $C_f$ factor is the mass of CO₂ emitted per mass of fuel burned, tank-to-wake. It is used in EEDI, EEXI, CII, and EU ETS carbon accounting. Values come from MEPC.364(79) Table 1.
| Fuel | $C_f$ (t CO₂ / t fuel) | LCV (MJ/kg) | Notes |
|---|---|---|---|
| Heavy Fuel Oil (HFO) | 3.114 | 40.2 | RMC–RMK grades per ISO 8217 |
| VLSFO (≤ 0.50 % S) | 3.114 | 40.5 | Same Cf as HFO; LCV slightly higher |
| ULSFO (≤ 0.10 % S) | 3.114 | 40.5 | For ECA operations |
| Light Fuel Oil (LFO) | 3.151 | 41.0 | RMA, RMB |
| Marine Gas Oil (MGO) | 3.206 | 42.7 | DMA, DMZ |
| Marine Diesel Oil (MDO) | 3.206 | 42.7 | DMB |
| LNG | 2.750 | 48.0 | Before methane-slip correction |
| LPG (propane) | 3.000 | 46.3 | - |
| LPG (butane) | 3.030 | 45.7 | - |
| Methanol | 1.375 | 19.9 | CO₂ depends on pathway - see methanol WtW |
| Ethanol | 1.913 | 26.8 | - |
| Ammonia | 0.000 | 18.6 | Carbon-free; N₂O & NH₃ slip handled separately |
| Hydrogen | 0.000 | 120.0 | Carbon-free at combustion |
Where Cf is NOT enough
$C_f$ covers only the combustion-step CO₂. For regulatory contexts that need full global-warming impact, you additionally need:
- CH₄ slip for LNG engines (Otto MS / Otto SS / Diesel have different slip rates)
- N₂O emissions for all engines (small but non-zero; larger for ammonia)
- Well-to-tank upstream - feedstock extraction, processing, and transport
The well-to-wake GHG intensity values in shared/fuel-factors.json capture all three and are used by FuelEU Maritime calculators.
Updating the factors
Values tracked in this table are the defaults. Operators with a supplier-certified carbon intensity (e.g. for a bio-methanol or e-ammonia batch) may substitute the certified value in regulatory reporting. When IMO issues an amendment to MEPC.364, update shared/fuel-factors.json in the repository and this page simultaneously.