Cost-benefit analysis of ships NOx Emission Control Areas (NECA) along China's coastal area.

Shipping, as a crucial pillar of global trade, generates significant amounts of nitrogen oxides (NOx), which profoundly impact the environment and public health. As a major global shipping nation, China faces severe challenges in NOx emissions reduction. This study constructs a bottom-up emission inventory model using Automatic Identification System (AIS) data and vessel profile databases to evaluate the feasibility and cost-effectiveness of implementing NOx Emission Control Areas (NECA) along the Chinese coastline. The results indicate that implementing NECA within 12 nautical miles, 50 nautical miles, and 100 nautical miles reduces NOx emissions by 8.3 %, 12.5 %, and 13.4 %, respectively. Among these, the 100-nautical-mile range achieves the most significant reduction, with a 48.8 % decrease in NOx emissions specifically from ships built after 2016. Among different emission reduction technologies, Selective Catalytic Reduction (SCR) proves to be more cost-effective and efficient than Exhaust Gas Recirculation combined with Water Injection (EGR + WIF) for long-distance voyages. In contrast, EGR + WIF demonstrates better economic performance in short-distance voyages and low-load conditions. Cost-benefit analysis reveals that expanding the NECA range to 50 and 100 nautical miles results in cost-benefit ratios of 2.93 and 3.86, respectively, confirming the significant economic and health benefits of this policy in larger areas. Despite high initial costs, the substantial long-term environmental and public health benefits justify the widespread implementation of NECA along China's coastline.