Diesel, Hybrid or Fully Electric Ferry: A Method For Operating Cost Analysis And Battery Size Optimisation

Public consciousness of global warming issues is driving the demand for short-haul ferries with fully electric, or hybrid propulsion systems. For hybrid systems design approaches to identify optimal energy storage and energy source configurations from a wide array of possibilities do not exist. Therefore, a strategy is proposed that allows optimal energy storage size to be determined, based on key voyage cycle parameters, before minimizing operating cost functions, based on a given energy source configuration. Cost function minimization is founded on a novel rule-based power management approach for hybrid electric ferries. The proposed strategy is verified through application to an actual voyage cycle. Three different power system configurations are compared; a hybrid system with two diesel gen-sets and an onboard-charged battery bank, a hybrid system with one diesel gen-set and a shore-charged battery bank, and a fully electric system. Using the proposed strategy quantified results for each configuration are determined, illustrating its utility.