Assessment of ship emissions in coastal waters using spatial projections of ship tracks, ship voyage and engine specification data

Abstract

To understand, mitigate and reduce the detrimental effects on human health and the environment from exhaust gas emissions from ships it is necessary to be able to estimate the quantity and location of these ship emissions in time. Currently, the two most commonly used ship emission assessment methods sit on opposite ends of the spectrum – the top-down approach, which provides low resolution yet efficient aggregated results however is unable to account for specific shipping activities, and the bottom-up vessel-by-vessel approach, which provides near-instantaneous ship emissions production at a high resolution – yet is data and time intensive. To address the market gap for a ship greenhouse emission estimation method that hybridises the best of both the bottom-up and top-down methods the novel Ship Emissions Assessment (SEA) method is proposed as an innovative hybrid solution. It is a cost effective and resource efficient method, presenting spatial ship emissions utilising widely accessible data, and it is precise – fulfilling the requirements needed to evaluate ship emissions reduction measures. Novel SEA method is the first in its endeavour to replace Automatic Identification System (AIS) Vessel-based raw data allocation, by using rapid analyses of readily available ship track density data and average voyage information. It combines obtained average voyage distance with voyage average speed to estimate ship activity for emission assessments - saving costs by reducing time and reliance on complex computations, especially when many ships need to be analysed simultaneously. Using the novel SEA method, a series of containerships from geographically diverse ports were sampled and assessed for emissions with comparative results confirming the representations equivalent to the detailed and data demanding bottom-up method. Subsequently, the novel SEA method was applied to containership traffic calling into the Port of Trieste, in the northern Adriatic Sea, where it demonstrated the ability to estimate and quantify historic emissions for the preceding 12 months while taking into account seasonal port traffic variations. The novel SEA method showed to be an efficient, inexpensive and accurate, easy-to-use emission assessment tool based on widely accessible data. It can be used in day-to-day shipping operations by a variety of stakeholders including port operations managers, regional traffic operators, and those non-industry, while providing the required level of technical accuracy. In comparison, existing methods are not as time and cost effective, user-friendly, nor based on easy to interpret and readily accessible data. The novel SEA method enables further global research of ship emissions, and for regional and international policy makers to effectively manage the measures needed to reach greenhouse gas emission reduction targets. • Ship emission estimation method hybridising the best of bottom-up and top-down . • Rapid and accurate estimation of airborne emissions from ships. • Assessing effectiveness of evolved and mandated NO x reduction measures. • Ship emissions estimated using widely accessible ship track density maps. • Estimated CO 2 , SO x and NO x containership emissions for the Port of Trieste.