A new study by UCL and UMAS has found that optimising port arrivals to consider port congestion or waiting times could reduce voyage emissions by up to 25 per cent for some vessel types.
The average potential emissions saving for the period considered (2018-2022) was found to be approximately 10 per cent for containerships and dry bulkers, 16 per cent for gas carriers and oil tankers, and almost 25 per cent for chemical tankers.
The study found that these ships spend between 4-6 per cent of their operational time, around 15-22 days per year, waiting at anchor outside ports before being given a berth.
Tristan Smith, Professor of Energy and Transport at the UCL Energy Institute, said: “The International Maritime Organization (IMO) set ambitious GHG reduction targets in 2023.
“Meeting those targets means unlocking all efficiency opportunities – including voyage optimisation and operations around ports.
“This will only happen if CII carbon intensity indicator remains a holistic metric covering all emissions, and incentivising shipowners, charterers and port stakeholders to break down long-running market barriers and failures.”
Over the period 2018-2022, chemical tankers, gas tankers, and bulk carriers spent increasing waiting times at anchor before berthing, rising to 5.5-6 per cent of time per annum, by 2022.
Waiting times for oil tankers and containerships stayed approximately constant (around 4.5 per cent and 5.5 per cent respectively). Some of the increase in waiting times may be attributable to the port congestion caused by COVID-19 and by a post-pandemic surge in maritime trade.
The study also found that smaller vessels generally experience longer waiting times, though this varies by vessel type. A previous report by the authors, Transition Trends, has shown that poor operational efficiency is one of the main reasons for increased emissions in the period 2018 to 2022.
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Dr Haydn Francis, Consultant at UMAS, said: “Our analysis highlights the current and growing issue of port waiting times and the inefficiency they represent. This is just one piece of the broader operational inefficiency puzzle that is key to generating the short-term emissions reductions that will need to be achieved before 2030.
“By targeting these idle periods, the IMO can unlock significant emissions reductions while also reinvigorating improvements in operational efficiency, which have stagnated since 2012.”
The waiting behaviour stems from the common operational practices such as “first-come, first-served” scheduling and the “sail-fast-then-wait” approach – and is exacerbated by systemic issues such as port congestion, inadequate data standardisation, inflexible charter parties (between ship owners and charterers), and limited coordination between the many wider stakeholders involved in a loading/unloading operation (port authorities, cargo owners etc.).
The study emphasizes that the Carbon Intensity Indicator (CII) regulation should encompass all aspects of a voyage, not just the ‘sea-going passage.’ This comprehensive approach encourages stakeholders to collaborate on reducing greenhouse gas (GHG) intensity across the entire value chain, rather than focusing solely on areas where shipowners or charterers have control.
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Limiting the CII to specific parts of the voyage would leave existing market barriers at the ship-port interface unaddressed, complicating efforts to meet the 20 to 30 per cent GHG reduction target by 2030, as outlined in the International Maritime Organization’s Revised Strategy.
Additionally, the study notes that port congestion contributes to inefficiencies, particularly affecting low-income member states in their decarbonization efforts. While not deeply explored in this study, this suggests a connection between improving efficiencies at the ship-port interface and enabling a just transition, which is vital for midterm measures.
