Carbon Intensity Indicator (CII) is a new measure based on an operational approach that supports the IMO’s objective “to reduce CO2 emissions per transport work, as an average across international
shipping, by at least 40% by 2030, pursuing efforts towards 70% by 2050, compared to 2008.”
Resolution MEPC.328(76) adopted at MEPC 76 in June 2021, will enter into force on 1 November
2022 and introduced amendments to MARPOL Annex VI with new requirements for:
- Operational Carbon Intensity Indicator (CII) and CII rating (Regulation 28)
- Enhanced SEEMP (Regulation 28)
The CII rating scheme is based on the operational efficiency of ships, which will be a measure of how
energy efficient ships are when transporting cargo and passengers.
What are the Annual operational carbon intensity indicator (CII) and CII ratings?
CII is the operational carbon intensity Indicator expressed in grams of CO2 per deadweight-nautical mile and it is a measure of vessel efficiency of CO2 emitted in transporting cargo. The CII and CII rating scheme will apply to all Cargo ships of 5,000 gross tonnage and above, that is, the ships which are already subject to the requirements of the IMO Data Collection System (IMO DCS).
The annual operational CII achieved or attained CII will be required to be documented and verified
against the required annual operational CII. This will enable the Flag state to determine the operational CII rating, the rating will be given on a scale from A to E, A being assigned to better performing vessels.
CII & enhanced SEEMP
Since 2019 it has been mandatory for us to fulfill the requirements of IMO’s data collection system. In this process we monitor Fuel consumption, Hours spent underway and Distance travelled within a calendar year, this data is then verified by an approved Verifier, they will additionally have to calculate the attained CII of each ship. Based on the attained and required CII, a CII rating will be assigned to a ship.
The attained annual operational carbon intensity indicator will be based on IMO DCS. The revised MARPOL Annex VI Regulations 5.4.6 and 26.3 requires that for vessels, where the CII requirement is applicable, should have their SEEMP III no later than 1st January 2023 to include:
- the methodology that will be used to calculate the ship’s attained annual operational CII and
the processes that will be used to report this value to the ship’s Administration - the required annual operational CII, as specified in regulation 28 of this Annex, for the next
three years - an implementation plan documenting how the required annual operational CII will be achieved
during the next three years - a procedure for self-evaluation and improvement
Attained CII:
| SHIP TYPES | ATTAINED CII CALCULATION METHOD | NOTE |
| Bulk Carriers, Tankers, LNG Carriers, Container ships, General cargo ships, Combination carriers | CO2 Emssion/ (Deadweight X Distance sailed) | Deadweight: Corresponding to Maximum Summer load draft |
| Cruise passenger ships, Ro-roships (vehicle carriers), Ro-ropassenger ships | CO2 Emssion/ (Gross Tonnage X Distance sailed) |
Required CII:
The required CII is calculated as:
Note: Z factors for the years of 2027 to 2030 to be further strengthened and developed taking into account the review of the short-term measure.
The required CII is calculated using 2019 as a baseline and a reduction factor will be applied every year from 2019 onwards, this means the ship will have to continuously achieve better performance each year to stay compliant or to maintain a preferred rating. Assuming a ship is rated as C in the year 2021 and not able to sustain this rating, the rating will decrease if the operator does not strive to continuously improve the operational performance of their ships.
Required CII rating is calculated using the CII reference lines for each ship type and a reduction factor is applied every year as shown in the above table.
Administrations, port authorities, and other stakeholders, as appropriate will be encouraged to provide incentives to better rated ships. For ships operating continuously for three years at Level “D” or for one year at level “E”, an improvement plan will have to be submitted to Flag and implemented, which outlines improvement to the vessel’s efficiency to a moderate level rating “C” or above.
MEPC 355(78) (CII guideline G5) describes about the interim guidelines on correction factors and voyage adjustments which may be applied to the calculation of the attained annual operational carbon intensity indicator (CIIship) of regulation 28 of MARPOL Annex VI, and as defined by the 2022 Guidelines on operational carbon intensity indicators and the calculation methods (CII Guidelines, G1) (resolution MEPC.352 (78)).
Framework of the operational energy efficiency performance rating:
An operational energy efficiency performance rating should be annually assigned to each ship to which regulation 28 of MARPOL Annex VI applies, in a transparent and robust manner, based on the deviation of the attained annual operational carbon intensity indicator (CII) of a ship from the required value.
To facilitate the rating assignment, for each year from 2023 to 2030, four boundaries are defined for the five-grade rating mechanism, namely superior boundary, lower boundary, upper boundary, and inferior boundary. Thus, a rating can be assigned through comparing the attained annual operational CII of a ship with the boundary values.
The boundaries are set based on the distribution of CII’s of individual ships in year 2019. The appropriate rating boundaries are expected to generate the following results:
- the middle 30% of individual ships across the fleet segment, in terms of the attained annual operational CIIs, are to be assigned rating C,
- while the upper 20% and further upper 15% of individuals are to be assigned rating D and E respectively, the lower 20% and
- further lower 15% of the individuals are to be assigned rating B and A respectively, as illustrated in the below figure.
Given the incremental operational carbon intensity reduction factors over time, the boundaries for defining performance ratings will be synchronized accordingly, although the relative distance between the boundaries will not change. The rating of a ship would be determined by the attained CII and the predetermined rating boundaries, rather than the attained CII of other ships. Note that the distribution of ship individual ratings in a specific year may not be always identical with the scenario in 2019, where for example 20% may achieve rating A, 30% may achieve rating B, 40% may achieve rating C, 8% may achieve rating D and 2% may achieve rating E in any given year.
Method to determine the rating boundaries:
The boundaries can be determined by the required annual operational CII in conjunction with the
vectors, indicating the direction and distance they deviate from the required value (denoted as dd
vectors for easy reference), as illustrated below figure .
Statistically, the dd vectors depend on the distribution of the attained annual operational CII of ships
of the type concerned, which can be estimated through a quantile regression, taking data collected
through DCS in year 2019 as the sample.
The estimated dd vectors after exponential transformation for determining the rating boundaries of
ship types are as follows:
By comparing the attained annual operational CII of a specific ship with the four boundaries, a rating can then be assigned. For example, given the required CII of a bulk carrier in a specific year as 10 gCO2/(dwt.nmiIe), then the superior boundary, lower boundary, upper boundary, and inferior boundary is 8.6, 9.4, 10.6 and 11.8 gCO2/ (dwt.nmiIe). If the attained CII is 9 gCO2/(dwt.nmiIe), the ship would be rated as “B”.
CII Monitoring
The CII is based directly on the fuel consumption, which is influenced by how a specific ship is operated in combination with its technical efficiency and fuel. Its value will be affected by the type of fuel used, the efficiency of each vessel and operational parameters such as vessel speed, cargo transported, weather conditions and the general condition of the vessel (e.g. biofouling).
A vessel can reduce its carbon intensity by a combination of measures:
- Speed reduction
- Optimization of operations and logistics
- Implementation of energy efficiency technologies
- Use of alternative fuels
