A ship emission estimation methodology with spatial mapping capability for assessing regulation effectiveness

Abstract

In response to global warming, the International Maritime Organization (IMO) set rules of 50% Greenhouse Gas (GHG) reduction by 2050, from 2008 levels. Signatory countries to the IMO’s regulation require frequent assessment of the contribution of GHG emissions from shipping calling at their ports or trading in their territorial waters to ensure their compliance with the regulations. This demands a rapid and accurate method to assess shipping’s contribution to GHG emissions. Current methodologies for estimating emissions from ships can be described on a scale between bottom-up and top-down methods. Top-down methods provide rapid estimates – primarily based on fuel sales reports - without considering individual vessel details. Therefore, they are less accurate and do not provide a breakdown of emissions by ship types or in specific regions. Bottom-up methodologies are detailed vessel-based estimates; however, they are data and time-demanding. The novel Ship Emissions Assessment method (SEA) fills the gap between bottom-up and top down methods by providing an innovative hybrid solution for rapid but accurate ship emission estimation. It uses publically available, cost-effective data sets previously unused for emission estimates. The SEA method was demonstrated for containership traffic in 2019 for three ports: Trieste, Rijeka and Venice. The CO2, SOx and NOx emissions were quantified per transported container (TEU). The SEA method requires from 1/500 to 1/50 of the data used by the equivalent bottom-up calculations, relying on AIS signals in a temporal resolution ranging from minutes to an hour. Consequentially, it requires 1/100 to 1/10 of the bottom-up processing time, providing results comparable to the detailed bottom-up methodology. This Thesis also explores the value of presenting emissions spatially on a ship density map with the example of CO2 production presented. The SEA method provides a simple and inexpensive tool for assessing emissions from ships and generates data for emissions per unit of cargo.