A Systematic Evaluation of Alternative Options for the Reduction of Vessel Emissions in Ports

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Transport operations are significant contributors to pollutant emissions across the globe. Maritime transport is responsible for approximately 3% of the global carbon emissions, while emissions around ports from vessel traffic and stationary ships also affect the local environment. This paper presents a framework for examining these impacts considering the environmental footprint of 1) ships approaching/departing and 2) berthing at ports, where their emissions impact directly on local air quality and on the exposure of the local population. Speed reduction of ships in transit and cold ironing for berthing ships are examined as possible mitigation techniques to illustrate their potential to reduce emissions for a range of different port and vessel types. Their scope is assessed per call per ship for the reduction of emissions for carbon dioxide (CO2), sulfur dioxide (SO2) and nitric oxide and nitrogen dioxide (NOx). Both methods are found to be effective, although the results are strongly dependent on the vessel specification and port operating characteristics. For speed reduction, key factors include the fuel used, the size of the vessel, its operating speed and the speed reduction policy adopted. For cold ironing, the port turnaround time, the source of shore electrical power and policies regarding fuel sulphur content are significant. While the two techniques can be applied independently, one of the two may be preferable in a specific port or for specific vessels. Reductions of 55.1 tonnes of CO2, 267 kg of SO2 and 2046 kg of NOx are seen for the combination of speed reduction for a large ship and prolonged berth duration using a representative shore electrical supply. These results suggest that policies and practices available to shippers can deliver environmental benefits; however, a clear appraisal for costs and benefits of alternatives is essential to inform effective policy development.

Transportation Research Board 92nd Annual Meeting