Economic and environmental trade-offs in water transportation

In recent years slow steaming has resurfaced as a fuel saving measure allowing ship owners to significantly cut operational costs. Reduced fuel consumption leads to lower levels of greenhouse gases and pollutant emissions. Port authorities have considered offering incentives to ship operators that significantly reduce sailing speedin the port proximity, as a means to improve local air quality.This chapter conducts a literature review on emissions modelling methodologies for maritime transport and develops a framework that allows the estimation of pollutant emissions under different sailing scenarios. The chapter presents existing regulations and port initiatives thataim to reduce maritime emissions. The merits of localise slow steaming near the calling port for various case studies including different ship size, trip distance, sailingspeed and fuel policies in place are examined. An activity based methodology is used to estimate fuel consumption and emissions savings during lower sailing speed operation for machinery on-board.Fuel price and the value of timelost govern the extent to which slow steaming and local speed reductions can be effective. The economic and environmental trade-offs occurring at different sailing speeds are discussed from the perspective of both the ship operator and the port authority considering the implications of regulatory policies such as the expansion of Emission Control Areas (ECA). The chapter concludes with a set of guidelines to port authorities on designing attractive speed reduction programmes, and recommendations to shipping companies on improving fuel efficiency across their schedule when such programmes are available