Environmentally differentiated port pricing
Port fees can be differentiated on the basis of vessels’ environmental performance. For example, if port fees were differentiated on the basis of emissions from vessels, lower emissions would translate into discounts on port fees. Although various ports have introduced green port discounts for a selected group of clean ships, few ports apply full environmentally differentiated port pricing to both dirty and clean ships.
The decision to implement such arrangements is usually taken by port authorities.
Port-based incentives promoting environmentally friendly maritime transport are among possible market-based measures that could help reduce GHGs and other emissions. Among the world's 100 largest ports in terms of cargo and containers handled, 28 already have port-based incentives. However, they hardly ever focus on reducing GHG emissions. Only five ports use indexing systems in which GHG emissions make up a substantial part of the evaluation that defines port fees.
The CO2 effects of green port tariff discounts alone are marginal, since this incentive does not target CO2 emissions and applies to relatively few ships and ports. Full environmentally differentiated port pricing, on the other hand, has significant potential, assuming the differentiation in tariffs between dirty and clean ships is large enough and the practice is more widely applied.
For example, one of the main global tools for differentiated port pricing is the Environmental Ship Index (ESI), developed by the International Association of Ports and Harbors. The ESI rates ships’ air emission performance, including a basic estimate of CO2 emissions, which accounts for 15% of the total score. Around 8 000 ships and 57 ports currently participate in the mechanism.
For a port offering discounted tariffs for green ships, the cost is essentially the amount of discount offered. While this practice is fairly common in large global ports, the cost limits its wider application. Environmentally differentiated port pricing, however, would entail applying environmental price differentiation to all ships calling at a given port. Dirty ships would cross-subsidise clean ships, and thus a port could apply such a system at no additional cost.
The co-benefits of differentiated port pricing depend on the environmental indicators included in the port pricing regime. Most such indicators generally focus on reducing emissions of conventional air pollutants, such as NOx, SOx and PM, rather than GHGs. The more indicators included, however, the less effective the system is likely to be in reducing CO2 emissions.
ITF (2021) Transport Climate Action Directory – Environmentally differentiated port pricing
https://www.itf-oecd.org/policy/environmentally-differentiated-port-pricing
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ITF (2018) Decarbonising Maritime Transport Pathways to zero-carbon shipping by 2035, https://www.itf-oecd.org/decarbonising-maritime-transport
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Styhre, L., von Bahr, J., Bergqvist R., Bäckström, S., Gonzalez-Aregall, M., Hult C., Jivén, K., Karlsson, R., Malmberg, L-G., Parsmo R., Rendahl P., Romson, Å., Sallander A-S., Sköld, S., Sterner, T., Vierth, I. and Winnes, H. (2019) Environmentally differentiated port dues. Gothenburg University (GU), Swedish National Road and Transport Research Institute (VTI), Port of Gothenburg, Ports of Stockholm, Port of Trelleborg https://www.ivl.se/download/18.14d7b12e16e3c5c362710c7/1574949624738/C365.pdf