Modelling Alternative Propulsion Technologies for Merchant Vessels

The planned IMO sulphur emissions limit will likely lead to price increases of low-sulphur distillate fuels from 2020 and beyond, and drive further pressure to improve fuel efficiency. The IMO measures planned for 2023 to meet the 2050 IMO CO2 reduction target will formalise the need for improved fuel efficiency through Energy Saving Technologies (EST). A wide variety of EST have been available for many years: the challenge lies in integrating and matching them to the ship’s operating profile to provide demonstrable benefit, and thereby improve adoption rates. With many ships operating in slow-steaming mode, there is opportunity for wind-based devices to contribute a larger proportion of the required thrust. This in turn provides scope to explore how reduced engine loads affect fuel efficiency, the use of air lubrication drag reduction and the use of wild heat from engine jacket water and exhaust gases to generate power. As part of a collaborative project with partners Black and Veatch, BMT has been developing the Vessel Technology Assessment System (VTAS) funded by the Energy Technologies Institute (ETI). This project has developed an approach that seeks to demonstrate the merit of ESTs fitted to specific ships on specific voyages. This paper presents the approach taken to use mathematical models of the ship’s power and propulsion system to identify the fuel saving benefits of a set of EST option designs. The performance before and after the installation of ESTs is modelled and the results compared to the baseline design.