The optimization of ship arrivals in ports through a reduction in congestion in port calls and in the time of departure waiting for ships could significantly reduce emissions produced by maritime traffic, a decrease that for some types of ships could reach up to 25%. This is stated by a new study created by the UCL Energy Institute of London and the fellow citizen UMAS, a consulting company that supports companies in the maritime sector in decarbonisation strategies. The The study examined ship traffic between 2018 and 2022 noting that ships spent between 4 and 6% in the period of their operating time, equal to about 15-22 days per year, in waiting outside the ports before being able to arrive at the quay, time to a wait that - the document specifies - derives from common practices systemic problems such as port congestion, from inadequate data standardization, from rental agreements not flexible between owners and charterers and by the limited coordination between the many stakeholders involved in a transaction loading and unloading of goods from the ship.

With a reduction in waiting time, the study points out, the potential average emissions savings would be around 10% for container ships and bulk carriers, 16% for gas carriers and oil tankers and almost 25% for chemical tankers. The savings of greenhouse gas emissions was estimated on the basis of the reduction in the speed of the journey which could be if the ships set sail to arrive in port at the time when when docking becomes available.

The document specifies that in the period 2018-2022 the average time of The number of ships has increased, a trend that varies from depending on the type of ship (it decreased for container ships and oil tankers). Among other findings, the study highlights that Generally, waiting times before docking are reduced with The increase in ship size: smaller ships have the longest waiting times before docking and therefore have the greatest potential for reducing the velocity.

The study also notes that greenhouse gas emissions could be reduced by converting waiting times into a Longer duration of the trip that can be performed at a lower speed: due to the relationship not between the speed of the ship and the consumption of fuel, in fact, a waiting time of 4-6% would convert into improvements in carbon intensity and reductions in significantly higher emissions (around 10-25%). He also noted that the potential for reducing total emissions for the different types of ships does not correspond to the types of ships that have the longest waiting times and reduction potentials of speed, the study specifies that, for example, the containerized maritime transport generally presents the time of lower expectations, but, since it is the type of ship with the highest total emissions, has the highest potential for reducing absolute emissions.

Examining ways to reduce waiting times of ships and therefore of the emissions produced by maritime traffic, The study could not fail to take into consideration the Carbon Intensity Index (CCI), the energy efficiency rating of ships related to the reduction of the annual reduction operational carbon intensity. An index of which the international shipowners' associations, in the context of the under definition at the International Maritime Organization (IMO), have asked for the change several times ( of 9 July 2024). UCL and UMAS study underscores validity of an approach based on this indicator: observing that there is already a solid literature that underlines how the potential to unlock further energy efficiency improvements in maritime transport is linked to the removal of market malfunctions, the document notes that "The CII regulation as it was conceived originally - a holistic goal-based approach to assess the measured annual overall carbon intensity (effective) - is logically consistent with this literature. It has set high goals in all operational aspects, including Operations that occur at the interface between different entities commercial sectors, for example between shipowners and charterers, as well as between ship operators and port/logistics operators. It is therefore understandable - the study notes - that it suffers criticism from industry stakeholder groups, particularly from the community of shipowners, because it acts on the shipowner and encourages him to find improvements not only on the ship, but also in the interfaces between the operation of the ship and the commercial environment and logistics in which shipping is placed. However- However, the study specifies - it is also clear from the analysis in this report that if the response to criticism is that to frame the CII metric only on the "sea voyage" (as some have proposed), this would change the nature of the regulation and would remove the incentive to find more holistic and potentially more holistic opportunities for the reduction of greenhouse gases and the intensity of carbon. Such a limitation would mean that the well-known barriers of the market with respect to the interface of the ship's operation would continue to have little incentive and would continue to persist. The perverse consequence would be to make it more difficult and/or expensive to achieve GHG reductions specified in the IMO's new strategy (20%, aiming at a absolute reduction of GHG by 30% in 2030, compared to 2008)".