Polar and Baltic icebreakers. Outside CII scope (operations vary wildly with ice thickness). Per-operating-day intensity is the most stable benchmark.
Formula
$$ \text{CO}2^\text{year} = \sum_j F_j \cdot C{f,j} $$
$$ \text{Intensity} = \frac{\text{CO}2^\text{year}}{d\text{op}} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $F_j$ | Mass of fuel $j$ | t | bunker log |
| $C_{f,j}$ | CO₂ factor | t CO₂ / t fuel | MEPC.364(79) |
| $Bench (Operating days / year)$ | operational benchmark | d | operations log |
| $d_\text{op}$ | Operating days | d | operations log |
IMO’s Polar Code imposes separate environmental constraints; icebreakers are otherwise outside MARPOL Annex VI’s carbon regime. LNG-fuelled and nuclear units are gradually displacing diesel-electric.
Sources
- IMO Polar Code (MEPC.264(68)).
- IMO MEPC.364(79) - Cf conversion factors.