The Attained GHG Fuel Intensity is the well-to-wake GHG intensity of the fuel mix consumed by a ship in the reporting calendar year, expressed in g CO₂-equivalent per megajoule of fuel energy on a lower-heating-value basis. It is the input to the IMO Net-Zero Framework compliance check (Required GFI and Direct Compliance Threshold) approved at MEPC 83 in April 2025.
Formula
$$ \text{GFI}_\text{attained} = \frac{\sum_j m_j \cdot LHV_j \cdot WtW_j}{\sum_j m_j \cdot LHV_j} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $\text{GFI}_\text{attained}$ | Attained GHG Fuel Intensity | g CO₂e / MJ | result |
| $m_j$ | Mass of fuel $j$ burned in the reporting year | t | IMO DCS report |
| $LHV_j$ | Lower heating value of fuel $j$ | MJ / kg | MEPC.391(82) Table 1 |
| $WtW_j$ | Well-to-wake GHG intensity of fuel $j$ | g CO₂e / MJ | MEPC.391(82) Table 1 |
The well-to-wake intensity comprises the well-to-tank (fuel production, refining, transport), the tank-to-wake CO₂ from combustion, and the tank-to-wake CH₄ and N₂O converted to CO₂-equivalent using the GWP100 metric (28 for CH₄, 273 for N₂O).
Default well-to-wake values (MEPC.391(82) Table 1)
| Fuel pathway | LHV (MJ/kg) | WtW (g CO₂e/MJ) |
|---|---|---|
| HFO (residual) | 40.2 | 90.5 |
| VLSFO 0.50% | 40.5 | 89.5 |
| MGO (distillate) | 42.7 | 88.3 |
| LNG, 4-stroke MS Otto | 49.1 | 86.9 |
| LNG, 2-stroke SS Otto | 49.1 | 80.7 |
| LNG, 2-stroke Diesel | 49.1 | 75.8 |
| Bio-MGO (UCO, net biogenic) | 42.7 | 4.8 |
| Bio-LNG (waste, net biogenic) | 49.1 | 19.7 |
| Methanol (grey, fossil) | 19.9 | 100.0 |
| Methanol (green e-fuel) | 19.9 | 5.5 |
| Ammonia (grey, fossil) | 18.6 | 127.0 |
| Ammonia (green e-fuel) | 18.6 | 12.0 |
| Hydrogen (green e-fuel) | 120.0 | 5.0 |
Sources
- IMO MEPC.376(80) - 2024 Guidelines on Lifecycle GHG Intensity of Marine Fuels.
- IMO MEPC.391(82) - 2024 Update to LCA Guidelines (default pathway values).
- IMO MEPC 83 (April 2025) - Net-Zero Framework approval.
See also
- GFI Compliance calculator - end-to-end Net-Zero Framework computation.
- Wiki: IMO Net-Zero Framework.
- Wiki: IMO GHG Strategy.
- Wiki: MARPOL Annex VI.