Amendments to the International Maritime Organization's (IMO) rules on ship carbon intensity and rating system entered into force on November 1 as part of the larger effort to decarbonize the shipping industry. 

This comes two months ahead of the mandatory energy efficiency calculations that will be required of all ships starting January 2023.

IMO's CII, EEXI rules enter into force

"Amendments to the International Convention for the Prevention of Pollution from Ships (MARPOL) Annex VI enter into force on 1 November 2022," IMO said in a statement, noting that this build on efforts first launched in 2011 and the framework of the Initial IMO Strategy on Reduction of GHG Emissions from Ships established in 2018.

IMO said these technical and operational amendments require ships to improve their energy efficiency in the short term and thereby reduce their greenhouse gas emissions.

The latest amendments for the first time apply the energy efficiency ratings not only to newbuilds but are extended with an "Energy Efficiency Existing Ship Index" (EEXI) which will be used to calculate the carbon intensity indicator. 

IMO noted that from January 1, 2023, it will be mandatory for all ships to calculate their attained EEXI to measure their energy efficiency and to initiate the collection of data for the reporting of their annual operational carbon intensity indicator (CII) and CII rating. 

The first annual reporting will be completed next year with initial CII ratings given in 2024. 

"Decarbonizing international shipping is a priority issue for IMO and we are all committed to acting together in revising our initial strategy and enhancing our ambition," said Kitack Lim, IMO secretary-general.

"These latest amendments build on energy-efficiency measures which were first adopted in 2011 and strengthened since - the CII and EEXI measures represent the next stage in our work to meet the targets set in the Initial IMO GHG Strategy," he added.

IMO said the short-term GHG reduction measures, adopted in 2021, form a comprehensive set of amendments to MARPOL Annex VI, which provide important "building blocks" for its future mid-term greenhouse gas reduction measures.

In explaining the new rules, the IMO said as a stimulus to reduce the carbon intensity of all ships by 40% by 2030 compared to the 2008 baseline, ships will be required to calculate two ratings: their attained EEXI to determine their energy efficiency, and their annual operational CII and associated CII rating.

Carbon intensity links the GHG emissions to the amount of cargo carried over the distance travelled.

Based on a vessel's CII, its carbon intensity will be rated A, B, C, D or E. The rating indicates a performance level, from best to worst.

A ship rated "D" or "E" for three consecutive years,  will then have to submit a corrective action plan to show how the required index of C or above will be achieved.

Shipping companies supportive but want changes

Meanwhile, some of the world's largest shipping lines signalled compliance and support for the objective of the IMO's latest regulations, but also noted the need for adjustments to the rules.

"MSC will support and fully comply with the CII regulation through a range of measures and we are very well prepared to do so," said Giles Broom, a spokesperson for MSC.

"As there are no net zero CO2 emission fuels available at scale to our industry in the short-term, MSC will continue to make energy efficiency performance improvements to help ensure that the fleet keeps pace with the evolving regulatory standards in 2023 and beyond."

Broom said this includes employing new designs and technology to modernize its fleet in order to increase energy efficiency performance.

The MSC spokesperson noted, however, that on top of a range of design and technology efficiency measures, "we have assessed that it will not be possible to achieve the required standards without a new program of voyage optimization that includes elements such as speed reductions and injecting additional ships into the network."

"Just-in-time port call optimization will also play a role," he added.

MSC then pointed out that changes should be made to the calculations. 

"As many across academia and industry have said, the calculation methodology (AER/DWT) should be revised to avoid unintended consequences that would distort the performance of a ship that spends a lot of time in port," Broom said, adding that  as things stand, the proposed methodology could lead to "situations in which a vessel’s rating would worsen simply because it spends more time in port."

"We respectfully question whether this unintended consequence could be avoided by amending the methodology," the spokesman added.

Maersk has also earlier said that "the CII does not incentivise cargo optimisation."

"CII should not effectively penalise vessels trading on shorter distances and while waiting alongside. It would be far better to have an operational indicator that would reward more productive ships, including based on cargo carried rather than on a theoretical value that may not correlate to transport work performed," Broom added.

The MSC spokesperson predicted that CII is expected to absorb about 7% to 10% of capacity across the global container fleet and expects changes in deployment patterns as the carriers would to balance the CII standards with the needs of customers.