Adverse Impacts of Chokepoint Transit Restrictions on Sustainable Maritime Transport: A Scenario-Based Emission Analysis in the Strait of Hormuz

The Strait of Hormuz is a transit point of vital importance to the global energy supply; however, the operational and environmental burdens caused by transit disruptions have not been sufficiently examined. This study uses a scenario-based methodology to quantify the additional fuel consumption and associated CO2, SOx, NOx, and PM2.5 emissions from waiting at anchor and low-speed maneuvering, particularly for energy-carrying vessels. It further provides a comparative examination of emission impacts at the vessel and fleet scales under crisis scenarios, dynamically characterizing the relationship between waiting time and emission increase. The analyses reveal that prolonged waiting and controlled transit substantially increase fuel consumption and, consequently, emissions. At a fleet scale of 28 vessels per week in the Strait of Hormuz, additional CO2 emissions reach 1401.12 tons under a moderate crisis and 2711.68 tons under a severe crisis, amounting to more than 10,400 tons of additional CO2 per month. Moreover, the local NOx and PM2.5 emitted by auxiliary engines idling at anchorage areas constitute a cumulative environmental risk to coastal air quality. Main-engine-related route deviation is most prominent at Suez, whereas a low-speed regime predominates at Malacca. These findings demonstrate that geopolitical friction at strategic straits entails not only energy-supply risks but also serious environmental harm. Consequently, chokepoint vulnerability assessments and energy security policies should holistically integrate vessel-level operational dynamics with maritime emission planning.