Port Call Optimisation is Key to Reducing Greenhouse Gas Emissions in Ports


Using SMART port technologies to facilitate ‘just in time’ ship arrivals has the potential to reduce greenhouse and pollutant gas emissions significantly at global container ports. Drewry’s latest research shows that targeting investment at ports with a disproportionate amount of waiting time will generate the highest benefits for the industry as a whole.

Shipping accounts for almost 3% of global greenhouse gas (GHG) emissions and for ports ocean-going vessels are typically one of the major contributors to GHG and pollutant emissions in the port area. Notably, ocean-going vessels and inland transport generate significantly higher emissions than the harbour-based support craft (i.e. tugs, pilot boats, etc) and cargo handling equipment that is under the direct control of companies situated within the port.

Ports have a significant role as facilitators of the decarbonisation of the shipping industry and in particular initiatives to reduce emissions originated by the operations mentioned above are essential. Considering ocean-going vessels, navigating, approaching and waiting are the key areas where emissions savings could be made.

A major element of avoidable GHG emissions in ports is the time vessels spend waiting at anchor before moving onto a berth. Using its proprietary AIS model, Drewry has analysed the performance of 193 of the world’s largest container ports, accounting for over 85% of global container trade, and showed that in 2023 total pre-berth waiting time remained 40% above 2019 levels. There is also considerable regional variation, driven by differences in traffic levels and port congestion.

In container shipping, berths are usually allocated on the basis of pre-booked slots (i.e. berthing windows), with multi-port schedules developed to enable on-time arrival at each port. Drewry’s analysis shows that despite a recovery from the supply chain disruptions incurred during the pandemic, a significant number of vessels have continued to operate on the basis of ‘sail-fast-then-wait’ which results in the earliest arrival time at the port, no matter whether a berth is available or not.

‘Just in time’ (JIT) arrival systems aim to reduce waiting by aligning vessel speed on inbound voyages with berth availability. They support the reduction of speed, lowering fuel consumption and emissions on the main voyage, and reducing the time spent and emissions generated at port anchorage zones.

Drewry’s tracking of port congestion shows that pre-berth waiting delays vary widely between ports in its global ranking, based on a combination of both total pre-berth waiting time and average pre-berth waiting time per 1,000 teu port throughput. Full details of the ranking and methodology can be found in the latest edition of Drewry’s Ports and Terminals Insight.

To illustrate the potential benefits of JIT arrival systems, Drewry analysed congestion hotspot Dar es Salaam, where last year vessels waiting at anchor for over one week accounted for almost 70% of total waiting time incurred at the port – which in 2023 totalled almost 2,000 days. We looked at what effect reducing the average speed on the inbound voyage would have on time spent in the port’s anchorage zones (speed reduction only applied to vessels incurring 8 hours or more of waiting time upon arrival at the port). The results indicated that capping average inbound voyage speed to 10 knots during congested periods would have generated waiting time savings of 31% – equivalent to 23,000 CO2eq of emissions. A more conservative scenario whereby average inbound voyage speed was capped at 12 knots generated waiting time savings of 16% (or 11,800 CO2eq).

Container shipping services typically call at multiple ports in a coastal or regional range, with order of port calls often dictated by geography. Greater coordination between these ports could help reduce their respective emissions from ocean-going vessels, particularly where voyage durations are relatively short, such as on the US East Coast. This would enable vessels to be given notice of berth availability conditions for their next port of call before departing their current call.

Drewry’s analysis of vessels departing from the US port of Norfolk with next port of call Savannah, which is located 450 nautical miles to the south, suggests that a selective speed reduction to achieve a 10-knot average speed (as a proxy for JIT) during congested periods could have reduced pre-berth waiting at Savannah by 24%, equating to a saving of almost 7,250 tonnes CO2eq. A 12-knot threshold would have generated waiting time savings of 6% or 1,800 tonnes CO2eq.

Implementing JIT arrival systems requires integration of port, terminal and carrier management systems, as well as the capability to interface with other service providers which play a key role in supporting ship arrivals and departures at each port. Hence, organisational challenges to implementing these systems are high, especially in emerging markets. Many of the ports with the highest potential to benefit are also likely to be the least prepared to implement these solutions.

While the potential for significant emission reductions are reduced if the underlying causes of longer waiting time, such as low berth productivity, are not addressed, Drewry’s view is that JIT arrival systems are well placed to deliver emissions reduction in the near term, and targeting investment towards ports with a disproportionate amount of waiting time will generate the highest benefits for the industry as a whole.

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Source: Drewry