Sizing of electrical generators in marine propulsion system for better fuel efficiency

In recently developed marine propulsion systems, diesel-electric generators (two for propulsion and one small generator for auxiliary load) are employed as power sources. Optimal sizing of these generators results better fuel use efficiency and lesser emission. Tugboat load cycle consists of loitering, transit and assist mode which is estimated an average engine load of around 20% of bollard pull (BP) capacity. A 60T BP tugboat system is considered in this research along with variable speed technology and analysis is made on sizing of generators and its effect on fuel consumption. From the results, it is observed that 3.1% fuel saving is possible in proposed system in comparison with a referred electric tugboat system. Techno-economic study is also carried out on the proposed system.