Assessment of Energy Efficiency for the Existing Cargo Ships

Abstract

In order to address the decarbonization policy, International Maritime Organization (IMO) has been dealing with energy efficiency of ships for more than a decade. Firstly, procedures for energy efficiency assessment are introduced through the regulative, but only for new ships. Consequently, IMO also introduced energy efficiency criterion for already built ships that is set to be applicable starting from 2023. Regulative is already having an impact on ship design. While the new ships can be adapted in design phase, built ones will not have so many options. So far, almost all the solutions include reduction of the speed, i.e., slow steaming. Nevertheless, there are numerous technical and operational measures. The paper presents the calculation of energy efficiency performed for the fleet of existing 11 cargo ships categorized into four different ship classes. Calculation is based on the current IMO regulations covering the evaluation of energy efficiency of existing ships index (EEXI). Input parameters for analysis are obtained using two approaches: technical files (design parameters of the ship) & sea-trial reports and statistical method (when technical files & sea-trail reports are not available). Authors examined if the difference in two input approaches and potential class notation change could lead to different energy efficiency evaluation results. Moreover, the main goal of the research was to investigate on how the present conventionally designed cargo ships compare to the novel regulations.