Techno-economic investigation of alternative propulsion systems for tugboats
Ömer Emre Karaçay, Osman Azmi Özsoysal
Abstract
In this paper, the main alternative propulsion systems based on internal combustion engines and batteries of a tugboat operating in harbour duties of the tugboat that include Emission Control areas are comparatively assessed. A hybrid propulsion system and two gas systems that one is with gas engines, other with dual-fuel engines are compared with a diesel system. For all cases, the harbour tugboats are investigated with 3 similar tugboat operation profiles. The gas and dual-fuel engines are assumed to operate using Liquefied Natural Gas and a small amount of diesel as pilot fuel, whereas diesel was regarded as the fuel for the case of the diesel engine propulsion systems. In the case of diesel-electric hybrid propulsion systems, the installation of hybrid components is also taken into account for reducing emissions and fuel consumptions. The propulsion systems are modelled and the techno-economical results were analysed in order to compare these systems. These results have been obtained by Life Cycle Cost that mainly consists of two main expenditures; Capital and Operational expenditures. Finally, these four alternative systems have been compared according to the calculated propulsion system costs for the 20-years operating period within the accepted assumptions and constraints.