An innovative model to design extreme emission control areas (ECAs) by considering ship's evasion strategy

Abstract

At present, ship emissions have become one of the three main sources of air pollution, and controlling the coastal emissions of ships remains an important issue both now and in the future. The establishment of emission control areas (ECAs) has become an effective measure, but compliance with ECA regulations will increase the cost of ships. To reduce costs, ship operators may formulate or adjust their sailing pattern (sailing speed and sailing path), resulting in evasion strategies. Ships' evasion strategies will inevitably affect pollution emissions generated from ships and the implementation benefits of the ECA. Thus, to achieve the expected emission reduction, it is necessary to incorporate ship's evasion strategy into the design and assessment process of an ECA boundary. However, the recently developed ECA boundary ignores ship's response strategy and lacks a quantitative design method, leading to unreasonable ECA boundary design and inaccurate emission reduction assessment.To address these problems, this paper defines extreme ECA boundary (the minimum ECA boundary to achieve the expected pollutant emission reduction), and for the first time incorporates ship's evasion strategy into ECA boundary design and assessment process. A procedure based on the convex hull of potential boundary points is proposed and nonlinear programming models are established to obtain the extreme ECA boundary. Furthermore, the effects of different factors on extreme ECA boundary design are quantitatively discussed. Finally, the pollutant emission reduction of the extreme ECA boundary is assessed and implications for the reduction of ship emissions are provided. The results show that the existing North America ECA boundary may make ships adopt evasion strategies on some routes, increase the relative fuel costs (30% before 2020 and 11% after 2020), and reduce the pollution emissions (57% of SOx and 51% PM emissions before 2020, and 68% of SOx, 3% of NOx, and 62% of PM emissions after 2020), but still not achieve the expected emission reduction target. While the proposed extreme ECA boundary can effectively prevent ships from adopting evasion strategies, has certain increase in relative fuel cost (42% before 2020 and 14% after 2020), and make more reductions in pollution emissions (more than 90% of SOx, 4.5% of NOx, and 80% of PM emissions both before and after 2020). As a result, compared to the existing ECA boundary, the extreme ECA boundary has better emission reduction and is more cost effective.