Evasion strategy for a coastal cargo ship with unpunctual arrival penalty under sulfur emission regulation

To comply with the sulfur emission control area (ECA) regulation, a ship can burn expensive MGO (marine gas oil) inside ECA but relatively cheap VLSFO (very low sulfur fuel oil) outside ECA. This paper investigates a coastal cargo ship’s evasion strategy, which refers to a detour decision that decreases its sailing distance within ECA and increases its sailing distance outside ECA to save fuel costs. To this end, a voyage cost minimization model is proposed to determine the optimal sailing trajectory and speed profile inside and outside ECA. A distinguishing feature is that the ship’s sailing time is endogenously determined, depending on the penalties imposed on early and late arrivals. The necessary and sufficient conditions are obtained so that the ship operators can quickly determine whether ECA evasion can save voyage costs. It is demonstrated that the evasion triggering condition depends on the fuel price ratio of VLSFO to MGO and the relative position between the ports and the ECA boundary. Compared with non-evasion, the ship operators have less incentive to arrive punctually under evasion. The proposed models are applied to compare the evasion behavior of ships operating in the coastal ECAs of China and the US. The resultant economic and environmental impacts of ship’s evasion behavior are further discussed from the government’s perspective. The numerical results suggest significant differences arise due to the different widths of the two ECAs.