The fuel cell powered superyacht

Abstract

One of the most important reasons to investigating fuel cells is the increased level of regulation regarding emissions in the maritime sector, while fuel cells offer the opportunity to reduce these emissions. It was not clear what the impact of these systems would be on a yacht, the aim of this project is therefore to gain more insight into these topics. The objective of this study was to investigate the impact on both the design and operation of a superyacht using fuel cells for energy supply on board. To reach this objective, first a review of different fuel cells and fuel technologies was executed. These conclusions are used to develop a decision making tool which will help in choosing between the different types of fuel and fuel cell techniques. Finally the tool is used to select the best possible fuel cell solution, for this option the impact on the design and operation of a fully fuel cell powered yacht is determined. The report is split up into two different parts, where in the first the technological review is carried out while the second part focused on the design study.

In the first part a study was conducted into the status and characteristics of different fuel cell technologies and fuel storage solutions. Seven different types of fuel cells are investigated which can divided based on their operation temperatures (Low, Medium or High). Fourteen different types of fuels which are categorised as physical-, fuel- or material based hydrogen. The density of both separate systems were analysed and merged into a combined density for comparison reasons. Other factors which have been investigated are the: storage type, maturity, safety, and emissions. To be sure that a good choice can be made despite the many variables, these review subjects are used as decision criteria for the developed tool. In addition, the time influence on the density is taken into account by the adjustable time factor which is integrated in the tool. Specific preferences for a system can be given by changing the weighting factor for the different decision criteria. When changing the weight factors the order of all options will be rearranged by the tool, showing the ranking of the most promising solutions corresponding to the preferences of by the user.
From this tool, it has become clear that a fuel cell solution should be specifically selected for any different type of application. A specific application could lead to the selection of a completely different type of technology, which is in contrast with a diesel combustion engine where only an appropriate size needs to be selected.

The second part focuses on the design study of a fuel cell powered yacht, whereby an Oceanco yacht was used as reference. The most promising fuel cell solution for this yacht was selected based on the decision making tool and selected weighting criteria, a high temperature PEM fuel cell powered by methanol turned out to be the best solution. In order to determine the influence of the conversion to fuel cells additional research has been performed towards other factors which have an impact on the design. The following subjects were considered: regulations, fuel cell characteristics, energy storage, propulsion and electrical distribution. From these topics, several important conclusions have emerged. First of all the regulations have a substantial impact on the design of a yacht. Secondly, the fuel and fuel cells itself require more space compared to the original configuration, and the fuel cells require a larger battery system to be able to follow the fluctuating load of a yacht. Lastly, it became clear that the use of fuel cells makes it possible to have some volume and efficiency gains when switching to PODs and a DC energy distribution system. A detailed design study based on these findings made clear that the yacht needed to become longer to fit all the required systems while keeping the functional requirements for the owners the same. Additionally the system changes corresponding to the fuel cell conversion resulted in an increase in terms of weight. These changes in length and weight turned out to have negligible change on the resistance of the yacht.
There are some factors which have an impact on the operation of the yacht. One of these is the fact that the lifespan of the used fuel cell technology is lower than that of a diesel combustion engine. A well designed hybrid system and by using shore power as much as possible, could be used to stretch the expected lifetime. Another operational issue could be the fact that this fuel cell technology is not fully developed which could influence the operability of the fuel cells. In addition, the methanol used as fuel is not as widely available as diesel. Positive influences are the fact that the overall efficiency increases while reducing all emissions with 100% except for the CO2 emissions which will be 14-20% lower compared to a diesel engine. When using green methanol, the overall emissions of the yacht will be completely reduced since it will be CO2 neutral. Additional advantages of fuel cells are the added comfort due to low noise and operation without any vibrations as well as an increased redundancy because of the modular design of the fuel cells.