Carbon Intensity Indicator (CII) Methodology
Inline with the International Maritime Organisation (IMO) guidance on ship carbon intensity indicators (CII), the application takes five datapoints to compute MARPOL Annex VI aligned CII Ratings:
- Ship Type
- Either Deadweight or Gross Tonnage (depending on the ship type)
- Distance Travelled in the calendar year
- Fuel Type(s)
- Amount of each fuel type consumed
From this minimal dataset, the IMO CII calculator computes the ship's IMO CII Rating, from to in the year. The app then uses projection techniques to backcast/forecast CII ratings for all other years between 2019 and 2030.
Rating
A ship's Rating for the year is then calculated by comparing its Attained CII Rating to its Required CII Rating.
The International Maritime Organization has published a set of boundaries, describing how close an attained rating was to a required rating. Those boundaries set the requirements to attain grades in the range A to E.
Ships nearer to their Required CII Rating acheive a grade of C, while ships outperforming trend towards grade A, and ships underperforming trend towards grade E.
| Ship Grade | CO2 Emission Boundary |
|---|---|
| A | Superior bound |
| B | Lower bound |
| C | Required CII range |
| D | Upper bound |
| E | Inferior bound |
Transport Work (W)
W = capacity × distance
A ship's Transport Work (W) for the year is the product of its capacity and its distance.
Depending on the ship type, capacity is measured by its deadweight tonnage or gross tonnage. The ship's travel distance is measured in nautical miles. Multiple different fuel types can be considered in this calculation.
Mass of CO2 Emissions (M)
M = fuel consumption × emissions factor
A ship's Mass of CO2 Emissions (M) for the year is the product of its fuel consumption and that fuel's emission factor.
Fuel consumption is measured in metric tons, kilograms, or grams. A fuel's emissions factor is attained from ISO 8217:2017, the current international standard for marine fuels.
Attained Carbon Intensity (A)
A = W × M
A ship's Attained Carbon Intensity (A) for the year is the product of its Transport Work (W) and its Mass of CO2 Emissions (M).
Required CII Ratio (R)
A ship's Required CII Ratio (R) is published by the International Maritime Organization in resolution MEPC.354(78).
Attained:Required Ratio (AR)
AR = A ÷ R
A ship's Attained:Required Ratio (AR) for the year is the quotient of its Attained CII Rating and its Required CII Rating.