Ship emissions and reduction potential under domestic policies and international cooperation: A case study in Hainan, China

Abstract

Ship emissions contribute considerably to air pollution and are expected to decline under domestic policies and international cooperation such as green shipping corridors (GSCs). However, evaluation of the emission reduction potential by the Domestic Emission Control Area (DECA) policy and GSC cooperation is still lacking. Here, a series of multi-year high spatiotemporal ship emission inventories around Hainan, a representative island province of China, were developed with the state-of-the-art Shipping Emission Inventory Model. The improved origin-destination identification algorithm allowed emission allocation to port level. The emission reduction potential of the DECA policy and Hainan's joining GSC was analyzed. In 2022, ship emission intensity in waters 12 Nm from Hainan (Hainan-12Nm) were 6.4 %-7.4 % of that in waters 12 Nm from China. From 2019 to 2022, Hainan-12Nm emissions dropped by 66.7 %-77.8 % for SO₂ and PM_2.5. Ideally, with adequate ultra-low-sulfur fuel, DECA can reduce SO₂ and PM_2.5 emissions by 16.6 % and 22.4 % yearly compared with no-DECA scenario. However, emission reduction would drop markedly if ultra-low-sulfur fuel is short in supply. Emissions of voyages passing through 200 Nm from Hainan took up 1 %-4 % of international shipping emissions, implying great emission reduction potential for Hainan's establishing GSCs, especially considering the flourishing South-South trade. This study provides a thorough assessment of the current state of shipping emissions around Hainan as well as offers excellent data support for Hainan to further advance the future upgrade of ship emission management policies.