Design of Hybrid Fuel Cell/Battery Systems for Maritime Vessels

Abstract

The work described in this thesis encompasses multiple aspects related to the development of hybrid marine power systems utilizing proton exchange membrane fuel cells and batteries. The focus is placed on the definition of methodologies that can help define the composition of the powerplant and its control. The developed methodologies are based upon a series of models that can simulate the powerplant, allowing the observation of the component’s behavior during operation. The analysis of the results obtained from simulations is used to evaluate the technical and economic feasibility of a specific powerplant configuration, and allows to set a benchmark for operation optimization. The first two Chapter of the thesis introduce the KPN H2Maritime project, and important aspects of hydrogen production, storage and distribution. The knowledge of these topics is fundamental in understanding the challenges encountered in relation to the adoption of hydrogen systems for transportation purposes. Such challenges are not limited to the technical limitations of fuel cells, batteries and power electronic components, but include a series of factors that are independent from the powerplant. Some of these factors are hydrogen safety, hydrogen storage and hydrogen production. Chapter three is dedicated to an overview of conventional maritime powerplants, hybrid electric powerplants and possible conversions into fuel cell/battery powerplants. The study of the conventional system, mainly the ones utilizing internal combustion engines, is fundamental as it sets a standard for performances and operational flexibility that has to be met by the newly designed hybrid systems. The definition of design criteria for hybrid powerplants utilizing proton exchange membrane fuel cells and batteries starts in Chapter four with the description of a quasi-static model to study the onboard power generation, storage and distribution during a vessel’s operations. The model is developed as a simulation tool and is used to define possible powerplant configurations based on the energy management strategy selected. The model is used as the base for the development of a software application developed in Matlab. Results obtained using the model can be used to study the technical and economic feasibility of the calculated configurations for the specific use case, or used as an input for validation into a dynamic model of the system. Two types of dynamic models have been developed and are described in Chapter five and six. These models allow to simulate the dynamic behavior of the powerplant’s components, and relative power electronics, replicating the operations of the system with a adequate degree of accuracy. Simulations carried out with the dynamic models allow a more in-depth observation of the component’s behavior during the vessel’s operations compared to the results obtained with the quasi-static model. Different powerplant layouts are tested, configuring the models of the components in different ways, and multiple energy management strategies are tested. The results obtained from these simulations can be used to compare different approaches to the powerplants configuration and control. Such results can also be utilized as a benchmark for further optimization or used as a starting point for laboratory simulations using hardware in the loop. The software and models developed for the H2Maritime project aim to fill a gap found in relation to the use high power hybrid system using fuel cells in the maritime transport industry. The development of design criteria and models to optimize operations for this type of hybrid system is key to make them an economically viable solution for ship owners. The identification of technical economic viability, even in a limited number of application, can spark the interest of many ship owners willing to innovate and to abandon polluting internal combustion engines. A transition to green hydrogen for a selected number of vessel would still imply a large reduction in the emission of pollutants and greenhouse gasses, reducing the environmental impact of maritime vessels, mitigating the effects of climate change and safeguarding marine and coastal environments.