A simulation-based approach for evaluating merchant fleet decarbonization strategies

Abstract

The International Maritime Organization (IMO) aims to reduce the annual greenhouse gas emissions from international shipping by at least 50 % by 2050, compared to 2008. To this end, the organization has adopted a set of regulations, including the Energy Efficiency Design Index (EEDI), the Energy Efficiency eXisting ship Index (EEXI), and the Carbon Intensity Indicator (CII), which will require the maritime industry to transition to lower carbon operations. However, the issue of how this transition is to be achieved remains unresolved. Against this background, this paper proposes a simulation-based approach for predicting how a selected fleet of merchant ships may develop over time under various decarbonization strategies. The aim is to make it possible to identify and evaluate feasible decarbonization strategies, accounting for potential bottlenecks, for instance in terms of the supply and availability of individual low-carbon fuels and technologies. A case study is presented in which the approach is applied to a fleet of 254 ships, which is assumed to be roughly representative of ships above 400 gross tonnage serving German ports.