Cargo-work-based CO₂ intensity per MEPC.1/Circ.684 - the oldest of the IMO operational intensity metrics and still used where actual cargo utilisation matters more than nominal capacity.
Formula
$$ \text{EEOI} = \frac{\sum_j F_j \cdot C_{f,j} \cdot 10^6}{\sum_i (m_i \cdot D_i)} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $\text{EEOI}$ | Energy Efficiency Operational Indicator | g CO₂ / (t cargo · nm) | result |
| $F_j$ | Mass of fuel $j$ burned in the reporting period | t | ship log |
| $C_{f,j}$ | CO₂ conversion factor for fuel $j$ | t CO₂ / t fuel | MEPC.364(79) |
| $m_i$ | Cargo mass carried on voyage $i$ | t | cargo manifest / BL |
| $D_i$ | Distance of voyage $i$ | nm | voyage log |
| $10^6$ | Unit conversion tonnes → grams | - | constant |
When to use
EEOI is sensitive to utilisation. A bulk carrier with DWT 82,000 carrying 50,000 t averages shows better AER than one carrying 80,000 t (same DWT denominator, similar CO₂), but the EEOI of the better-utilised ship is lower. Use EEOI for tramp trades, ballast-heavy patterns, or internal fleet-utilisation metrics.
Sources
- IMO MEPC.1/Circ.684 - EEOI guidelines.
- IMO MEPC.364(79) - Cf conversion factors.