Session: 07-01-01 Arctic Sea Transportation and Environmental Impact

Paper Number: 121555

121555 - A SENSITIVITY ANALYSIS OF THE VOYAGE ADJUSTMENT FOR SAILING IN ICE OF THE CARBON INTENSITY INDICATOR REGULATION 

The Carbon Intensity Indicator (CII) requirement came into force in 2023 through an amendment to the IMO’s International Convention for the Prevention of Pollution from Ships (MARPOL). The objective of the CII requirement is to reduce greenhouse gas (GHG) emissions. The annual operational CII value is the ratio of carbon emissions to transport work, and the regulation mandates the CII value of each vessel type to be within a specific range. Ice-classed vessels have been granted an exemption from the CII requirement. The exemption allows ice-classed vessels to exclude from the calculation of CII the part of any voyage that constitutes sailing in ice. The rationale for the exemption is that navigating in ice requires more energy than operating in open water, so the exemption is a means of compensating for such operations. Our research suggests that the exemption is likely to influence tactical decision-making so that operators can maximize the potential benefits allowed by the regulation as defined. For example, in some circumstances, an operator may choose to sail along the ice edge (rather than well clear of it) in order to qualify for the exemption. Further, as the fuel consumption along such a route is exempt from the CII calculation, the operator does not have the corresponding incentive to operate “efficiently”, so may in practice sail at relatively high speeds to reduce the total voyage time. Consequences arising from this scenario include higher emissions and increased risks associated with sailing along the ice edge, possibly at relatively high speeds. This is contrary to the objective of CII.

The current study examines the exemption further by performing a sensitivity analysis of definitions for sailing in ice conditions. Sailing in ice as defined in the current regulation expresses that the ice-classed vessel is operating in sea ice, while alternative definitions are more specific in terms of ice concentration and ice thickness of the ice field in which the vessel operates. We present a case study of a conventional diesel powered bulk carrier with ice class IA Super on a voyage in the Canadian Arctic. Routing of the vessel is optimized based on an assumed rewards function, a routing algorithm, and a ship performance model (to evaluate e.g. fuel consumption and voyage time). We compare the routes selected under different definitions of “sailing in ice conditions”. The results show that different definitions of sailing in ice conditions lead to different optimal routes for the vessel, some of which are more effective than others in meeting the IMO’s strategic objective of reducing GHG emissions. This may be of interest to stakeholders in connection with future modifications to the CII regulation.

Presenting Author: Trung Tien Tran Memorial University of Newfoundland

Presenting Author Biography: Trung Tien Tran is a Ph.D. candidate at the Memorial University of Newfoundland. He received a Master of Engineering degree from Memorial University in 2021. He is interested in applying machine learning methods in route optimization for vessels through ice-covered waters.

Authors:

Trung Tien Tran Memorial University of Newfoundland
Thomas Browne National Research Council of Canada
Brian Veitch Memorial University of Newfoundland