SOFC & Battery hybrid experimental proof of concept and transient simulation for maritime load following

Abstract

Transportation in the maritime sector is responsible for a significant part of the global anthropogenic greenhouse gases and emissions. Furthermore, air pollution from international shipping is identified in coastal areas of Europe to be responsible for a substantial number of yearly premature deaths from cardiopulmonary disease and lung cancer. Therefore, the International Maritime Organization (IMO) has envisaged a 40 % reduction of CO2 emission by 2030 and 70 % by 2050, with SOx, NOx and, black carbon emissions reductions by 80 % compared to the baseline of 2008. In order to achieve these goals, solid oxide fuel cells (SOFC) have the potential to play a major role in power generation on board, due to their high fuel efficiency, fuel flexibility, and very low emissions. One challenge is that SOFCs by themselves are currently unable to cope with the high power gradients that are partly characteristic of the power demand profiles of ships. To improve their load following behavior, they can therefore be coupled with batteries in a hybrid system. The European project Nautilus aims to develop a pilot marine genset system consisting of an SOFC & battery hybrid to operate with LNG. This contribution will present experimental results of the hybrid genset proof of concept, consisting of a 30 kWe SOFC module coupled to a 40 kWh Li-ion battery. The proof of concept was operated using a rule-based control strategy to determine the power split for the SOFC and the battery. The results show that the time-varying power demand representative of a ship's load profile can be met at all times while the battery state of charge is integrated in the control algorithm of a specially purposed energy management system. Gas analysis was further used in order to confirm the fuel utilization of the SOFC. In addition, a transient 1D+1D SOFC model was validated based on experimental results of the SOFC and battery characterization, and applied to carry out pre-simulations to test the rule-based power split control strategy prior to the experiments. The results enable a next step in the scaling process towards the construction of a scaled-up demonstrator over the course of the running year.