Running ships more efficiently could dwarf other emissions reduction strategiesRunning ships more efficiently could dwarf other emissions reduction strategies

Ditching the frequently used ‘sail fast, then wait’ mantra could slash emissions by huge margins, a joint study undertaken by University College London (UCL) and the consultancy, University Maritime Advisory Services (UMAS), has found.

The consultants analysed ship movements over a four-year period between 2018 and 2022 and found that potential emissions savings averaged 10% for container ships and bulk carriers; 16% for gas carriers and oil tankers; and close to 25% for chemical carriers. On average, ships spent 4-6% of their time – 15-22 days a year – waiting to berth.

Over the four-year period, waiting times rose to 5.5-6% for chemical tankers, gas ships, and bulk carriers. However, some of the increase in waiting times could have been attributable to Covid-induced port congestion, the analysts said. The times for container ships, 4.5%, and oil tankers, 5.5%, remained much the same.

Dr Tristan Smith, Professor of Energy and Transport at the UCL Energy Institute pointed to the significance of the IMO’s carbon intensity indicator (CII). “The IMO set ambitious greenhouse gas 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 remains a holistic metric covering all emissions, and incentivising shipowners, charterers and port stakeholders to break down long-running market barriers and failures,” he said.

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The consultants noted that the study demonstrates that the CII regulation should take into account every part of a ship’s voyage, not just the ‘sea-going passage’, as some have proposed. This would focus attention on the greenhouse gas intensity of ships along the entire maritime value chain, instead of merely isolating the parts over which shipowners or charterers exercise control.

UMAS Consultant and joint author of the study, Dr Haydn Francis, said: “Our analysis highlights that the no value-add emissions associated with port waiting times are a current and growing issue across the shipping sector. This is just one piece of the broader operational inefficiency puzzle that can be targeted to generate the short-term emissions reductions that will need to be achieved before 2030. By targeting these idle periods, the IMO can help unlock significant emissions reductions while also driving broader improvements in voyage optimisation and overall operational efficiency.”