Batteries for marine applications

Abstract

The significant reduction in environmental emissions stated by the new IMO legislation, which specifies an amount of sulphur in fuels below 5% for 2020 and a NOx limit with an 80% reduction respect to the actual IMO limit within SECAS´s for 2016, aim the use of batteries as a propulsion source in hybrid marine power plants.Offshore vessels fit perfectly in the application of hybrid propulsion systems due to the large variations of energy requirements during their operation. Besides the reduction of emissions, the optimal combination between engines and batteries can be used for fast transients, smoothing the load of the engine and hence reducing the fuel consumption.The reasons behind the selection of the Lithium Ion battery as an ideal candidate for marine applications are stated in this thesis, through the comparison between the characteristics of different battery types.Simulation models of a Lithium Ion cell and a Lithium Ion battery pack at three complexity levels are developed in this thesis (simple, isothermal and thermal). Bond Graph approach is used for the model generation and 20Sim is used to perform the simulations.A safe operation window is stated for all levels since the performance of Lithium Ion cells is dependent on both, the temperature and the operating voltage. Therefore, both values must be kept within determined limits in order to avoid permanent damage in the cell.In case of the isothermal and thermal approaches, the electrochemical behaviour in the cell is considered and the main phenomena involved is represented, including: activation, conduction and diffusion, as well as, the dynamic effect of the electrochemical reactions and the heat release due to Joule heating.