Shaft-Generators in Ships: Techno-Economic Sensitivity Analysis Study

Abstract

Nowadays the propulsion electrification of ships is under intensive research. During this course, a very attractive option is the use of shaft electric machines, which is an intermediate step between the classic ship configuration and the all-electric one. However, two problems arise: (1) power dispatch should be carried out based on the Lagrange method or dynamic models, instead of simplistic methods related to the proportional rule of nominal active powers of generators, which is currently used in ships, (2) the installation of shaft generators should be examined systematically from the economic point view. In previous papers, the authors have solved the first one. In this paper, the mathematical basis for the techno-economic study of the installation of shaft generators in a ship is presented. It is using power dispatch based on the Lagrange method and is taking into consideration the basic technical limitations of the engines. Afterwards, it is applied in a general purpose ship and sensitivity analysis is carried out with respect to fuel price, operational life period, rate of interest, ship propulsion power duration curve etc. The results indicate the main factors which influence the economic sustainability of using shaft generators.