Today’s necessity- and goal to reduce carbon emissions in tandem with finite fossil resources and rising oil prices, demand for an alternative and cleaner energy source to power the world dredging fleet. In parallel, recent research in naval architecture iterates the potential role for nuclear-based propulsion on board of ’energy-intense’ merchant vessels (approx. 20 MWe+ installed power) [16][20][23]. Powering a (large) trailing suction hopper dredger (30.000m3+) by an on-board small modular nuclear reactor would cut direct greenhouse gas emissions by 100%.

The power demand on board of trailing suction hopper dredger is fluctuating continuously. A reactor is typically applied for supplying constant power. The objective of this thesis was to research the transient load capabilities of a nuclear-powered trailing suction hopper dredger.
First, for the on-board nuclear installation, a graphite-moderated high temperature gas reactor was opted for which is cooled by helium gas. This reactor type has a technology readiness level of 9 and small-modular-reactor concepts of this type are being developed. Both the open- and closed helium Brayton cycle concepts show greatest potential for power conversion. It was shown that the reactor, the heat exchangers and the turbomachinery play an important role in both the overall efficiency of operation and the transient load limits of the system as a whole.

Second, a thermodynamic model was built to be able to simulate the effects of different control mechanisms in realising load-following. Bypass- and compressor throttling control performed best and allowed the reactor to ramp down at lower rate, which is a favourable feature. For a 100% reduction in power output, the reactor would have to ramp down to 47% and 34% of nominal power respectively.

Third, it was investigated how the limitations in load-following would effect the operational profile of a HTGR-powered TSHD. The suggested closed helium Brayton cycle cannot perform adequate load following to the fluctuating demand of a conventional TSHD today without an auxiliary source of energy. When keeping reactor ramping rates below 10%/minute, a 25MWe HTGR-powered TSHD would see peaks in power imbalance up to 10 MW. However, a 3MWh ESS was considered to perform power take-in and power take-off. In presence of such auxiliary power source, the operational profile of a TSHD would not have to be changed.

Looking ahead, it is crucial to investigate the impact of repetitive power transients on the controllability and lifespan of both the reactor and other components within the power cycle. Additionally, a more in-depth study of the aerodynamic characteristics of the helium turbomachinery is necessary. Lastly, incorporating supplementary nuclear kinetics analysis could help validate the findings presented in this report.

Nuclear energy has found widespread application in navies across the globe. This thesis explores the potential integration of generation IV (very) Small Modular Reactor (SMR) technology for future surface combatants, focusing on the Very High-Temperature Reactor modelled as vSMR and a Molten Salt Reactor as SMR. The design impact of using generation IV (v)SMR technology for power generation on future surface combatants was unexplored. An estimation of future power and energy requirements and a detailed investigation of the reactor compartment is performed. It includes shielding, power generation, distribution, and conversion systems. Emerging naval-directed energy weapons and advanced sensor technologies are implemented to position the combatant within the spectrum of future mission capabilities.
A sizing model evaluates the feasibility of (v)SMR integration in terms of power, energy, volume, and weight. An indication of the available weight for (v)SMR technology is searched by iterating over the displacement of future surface combatants. For the defined future surface combatant, naval SMR power plants are compatible in terms of weight with conventional all-electric gas turbine-driven combatants with displacements above 8,000 tonnes. The model reveals that vSMR technology faces significant challenges related to weight despite its potential benefits in terms of redundancy and modularity. For combatants up to 16,000 tonnes, naval vSMR power plants are not viable due to their substantial weight and space requirements, primarily driven by the need for extensive shielding. Increasing the power output per vSMR reduces the required shielding and provides an alternative solution.
A case study explores a preliminary design of a future surface combatant with a displacement of 9,800 tonnes. The study suggests that the propulsion demand significantly impacts the size of the power plant. This results in the need for energy storage systems that manage variable power demands, particularly for SMR technology integrated into large surface combatants. Unlike vSMR naval power plants, SMR technology is comparable in size to the all-electric gas turbine power plant of conventional surface combatants.
The study assesses the effectiveness of the preliminary design in terms of survivability, mobility, range and endurance. It is estimated after capability prioritisation that (v)SMR technology and conventional gas turbine configurations have an equivalent survivability impact. A critical trade-off is highlighted between enhanced endurance and range against challenges, such as an increase in weight, volume requirements, and compromises in mobility compared to conventional gas turbine systems. The choice between SMR and vSMR technologies further complicates this balance by choosing between compactness and load response. A essential conclusion is that generation IV (v)SMR technology can enhance a future surface combatant's autonomy and future power load capabilities without compromising its effectiveness.
The Royal Netherlands Navy can use the results as an indicative substantiation for developing generation IV (v)SMR-powered future surface combatants. Moreover, it can help initiate a future naval capability plan and contribute to the realisation of generation IV (v)SMR power generation for the maritime sector.

The study seeks to reduce emissions in the shipping industry by exploring a propulsion system based on hydrogen internal combustion engines (H2ICEs) and liquid organic hydrogen carrier (LOHC) technology. While both technologies are strong contenders for future propulsion systems, their combined use has not yet been extensively researched. However, this combination could be both feasible and advantageous, and similar integrations have been studied for other hydrogen power systems.
A literature review is conducted on the integration of LOHC reactors with proton exchange membrane fuel cells (PEMFCs), solid oxide fuel cells (SOFCs), and H2ICE, specifically focusing on the hydrogen carrier H18-DBT. H18-DBT can store 6–8 wt.% hydrogen and comes close to meeting energy density requirements, although dehydrogenation losses are significant. Decreasing dehydrogenation losses is possible through waste heat recovery (WHR). DBT is favored for its low flammability and toxicity and high commercial availability, but environmental and viscosity issues remain.
The study identifies gaps in the literature by examining hydrogen carrier-based power systems, focusing on heat utilization methods for dehydrogenation, and quantifying the potential of WHR to improve system efficiency and exercise. This is especially relevant for H18-DBT due to its high dehydrogenation enthalpy.
For SOFC systems, the literature review concludes that direct heat transfer from high-temperature exhaust gases significantly enhances system efficiency and energy. Given an optimized design, WHR from SOFCs can fully support the dehydrogenation energy requirement under dynamic loads, which benefits overall system performance. In contrast, for PEMFC systems, WHR poses challenges due to the low-grade heat available, but preheating DBT before reactor entry improves efficiency. However, existing integration studies for PEMFCs may be overly optimistic, as they do not account for energy destruction at higher current densities. Nonetheless, coupling PEMFCs with LOHC reactors remains feasible and beneficial for system efficiency.
The integration of H2ICE with LOHC reactors and WHR appears promising based on the availability of high-temperature exhaust gases, similar to SOFC systems. The literature on port fuel injection (PFI) and direct injection (DI) H2ICE technologies shows potential for efficiency gains through WHR from exhaust gases and coolant.
To assess the efficiency improvements from WHR in H2ICE and their overall feasibility, this study proposes a system design and develops a model that simulates mass and energy balances for all operating points of an H2ICE. This model allows for comparison with other potential propulsion systems. A conceptual system-level model is created using MATLAB to analyze the WHR and coupling potential of H2ICE with LOHC reactors. The model uses two empirical engine models (for DI and PFI, respectively) and two reactor modeling approaches: a basic thermodynamic model and a kinetic model.
The model iterates until the reactor and H2ICE operating points are feasible with respect to the mass balances and determines the optimal reactor setting requiring minimum heat for dehydrogenation. It also calculates the mass flow for a hydrogen burner to estimate the additional hydrogen needed for complete dehydrogenation if WHR is insufficient. Available exergy and heat fluxes are calculated to provide a comprehensive review of the energy balance and WHR effectiveness.
Understanding the mass and energy balance is crucial for assessing the operational capabilities of these systems. The model reveals that while WHR integration in H2ICE is beneficial, it is not sufficient to sustain dehydrogenation at all operating points for H18-DBT.
The results indicate that coupling the dehydrogenation reactor with H2ICE is feasible and yields efficiency gains through WHR from exhaust gases and coolant flow. WHR integration with the thermodynamic reactor model reduces hydrogen combustion in the burner by 40% to 60%, increasing overall efficiency by 18.75%. In a 1D heterogenous model, the results were more promising: above 2,500 RPM, enough heat was available to sustain the dehydrogenation reaction. Nevertheless, concerns remain about the 1D model’s analytical derivation equation, as it may underestimate the dehydrogenation heat requirements.

This graduation thesis studies the CI combustion of ammonia and hydrogen in an ICE. It contains a review of the literature and a modeling study of the ignition and cylinder performance of the AmmoniaDrive test engine. AmmoniaDrive is a NWO-funded research project that aims to decarbonize shipping by introducing an ammonia-fuelled SOFC-ICE power plant for ships and other heavy-duty applications.
Ammonia (NH3) has unfavorable properties for combustion, such as a high heat of vaporization, narrow flammability limits, a high flame quenching distance, low flame speed, and most important: a high resistance to autoignition. Those properties have to be overcome and hydrogen (H2) is known to be capable of playing a role. As the properties of hydrogen are extremely high combustion speed, very wide flammability limits and a very short flame quenching distance. Unfortunately, both ammonia and hydrogen have a high resistance to autoignition, while CI engines need a fuel with low resistance to auto-ignition. For this reason, a carbon-based fuel, like DME or HVO, is considered necessary to achieve ignition.
The state-of-the-art experimentally achieved combustion concepts are an homogeneous charge compression ignition (HCCI) combustion concept of Pochet et al. [2020a] and an reactivity controlled compression ignition (RCCI) combustion concept of Chiera et al. [2022]. The HCCI combustion concept is fueled by NH3 and H2, without a carbon-based fuel. However, it requires a compression ratio (CR) of 22, a high intake temperature, and is limited by the maximum pressure rise rate (MPRR). The RCCI combustion concept is fueled by NH3 and diesel. This concept can achieve up to 81%e NH3, but still requires 19%e diesel.
A modeling study is done to investigate how to improve the CI combustion strategies, taking into consideration the context of AmmoniaDrive. The modeling study consists of two closed volume single-zone thermodynamic reactor models: the ignition model and the engine cylinder model. The ignition model is a constant volume model, resembling top dead center (TDC) conditions. The engine cylinder model simulates a closed volume from bottom dead center (BDC) to 90 CAD after TDC and incorporates volume change and the heat loss. Bothmodels make use of the chemical kinetic mechanism of Shrestha et al. [2018] to incorporate the combustion reaction. Due to the limitation imposed by the available species in chemical kinetic mechanisms, the carbon-based fuel in the modeling study is DME. For the future, hydrotreated vegetable oil (HVO) seems a more favorable carbon-based fuel, based on experimental results in a constant volume combustion chamber (CVCC) of Hernandez et al. [2023].
The results of the two models indicate that an HCCI combustion concept of ammonia and hydrogen, without a carbon-based fuel, will not ignite within the engine limits of the AmmoniaDrive test engine. An HCCI combustion concept of ammonia, hydrogen, with DME will ignite, but has a limited power output due to the MPRR. An RCCI combustion concept with stratification of DME throughout the cylinder looks promising based on the engine cylinder model results. Stratifying DME concentration, and with that the fuel reactivity, is likely to reduce the MPRR. This would allow for a higher power output due to the possibility to injectmore fuel energy without exceeding the engine limits.
Combining the literature and modeling results, it is likely that an RCCI combustion concept with ammonia, hydrogen, and HVO will lead to a higher power output and a decreased required amount of carbon-based fuel, whilst staying within engine limits.

The research objective of this thesis is to simulate the dynamic behaviour of a proton exchange membrane (PEM) fuel cell system. The model will encompass the fuel cell stack and some simplified balance of plant components. It will focus on simulating the reactions of the cell and the system with regards to changes in the requested load.

Traditionally, the control point (CP) of a dynamically positioned vessel is located around its center of gravity (CoG). However, during offshore operations, other locations, such as the crane tip or gripper position, become more critical due to the load being located there. This thesis proposes shifting the control point from the CoG to an alternative location, specifically the gripper position, to minimize the DP footprint at this location. Minimizing the DP footprint at the gripper location could lead to smaller motion deviations at this critical point. Consequently, this could potentially improve the workability of the vessel, which in turn could lead to higher operational yields. Additionally, the risk of potential damage and unsafe situations offshore is mitigated.

The conventional DP system contains a Kalman Filter, to filter out the first-order motions, a P(I)D controller that calculates the demanded forces to keep the vessel in place, and a thruster allocation algorithm that distributes the demanded forces to all the thrusters in an optimized way.

A new design for a DP system with the control point at the gripper position for the Deepwater Construction Vessel (DCV) Aegir is presented and evaluated. Time domain simulations were performed with the Aegir containing its conventional DP system and with the Aegir containing the newly designed DP system. These time domain simulations were performed using Orcaflex, which contains a model of the Aegir. This model of the vessel is connected to an external Python code, that contains the DP system, including a thruster allocation.


As the new DP system at the gripper location has to cope with coupled equations of motion, it is equipped with a new Multiple-Input-Multiple-Output (MIMO) PD controller, that consists of a decoupling module and separate PD controllers for each DOF. To obtain state estimates for the second-order motions at the gripper location, the state estimates calculated by the Kalman Filter are translated to the gripper location.

The effects on DP performance were assessed by evaluating and comparing the motion responses in the horizontal plane and DP footprint at the gripper location of both models. Also, the thruster behavior and energy consumption of both models are compared. This was done for an incoming wave direction of 135 degrees, a peak period (Tp) of 8 seconds, and significant wave heights (Hs) from 1.0 m to 2.0 m with increments of 0.5 m. The wave spectrum used is a JONSWAP spectrum. As recommended by the classification society, three-hour simulations are performed for the so-called 'base case' sea state with Hs = 1.5m. However, due to the extensive simulation time only one-hour simulations were performed for the cases with Hs = 1.0m and 2.0m.

When comparing the motion responses, one of the most remarkable results is an improved yaw response for the gripper control point model in all sea states that are considered in this study. Further on, the motion responses for sway appeared to be bigger for the gripper control point compared to the center control point in Hs = 1.5m and Hs = 1.0 m. However, the differences in sway are observed to be marginal for Hs = 2.0m.

The results show that the DP footprint has slightly improved in the x-direction for the gripper control point model compared to the center control point model for the base case. The same observation is done for Hs = 2.0m, but the differences found between the models in Hs = 1.0m are marginal. Also, the DP footprint was observed to be slightly larger in the y-direction for Hs = 1.0m and Hs = 1.5m for the gripper control point.

The total thrust outputs as delivered by the DP system during the simulations were converted to power, by using the propeller diagrams (for DP-speed state) for the specific types of thrusters the Aegir is equipped with. From these results, it became clear that the gripper point control model consumes less energy in all tested sea states compared center control point model.

From the results presented in this study, it is concluded that the system itself has potential, but no hard conclusions can be drawn for the system in its current form. Problems were observed with the current thruster allocation algorithm from HES, which need to be explored in more detail and resolved. It is recommended to look into developing a stable working thruster allocation algorithm for both control point models, such that more accurate dynamic simulations can be performed and the system can be assessed under more sea states.

This thesis delves into the intricate process of formulating an answer to the pivotal research question:

"What are the design characteristics of an economic high speed nuclear container vessel?"

The report systematically unfolds in six chapters, primarily focusing on a comprehensive literature study.

The exploration begins with an in-depth analysis of various nuclear reactors, emphasizing aspects such as load following, capital costs, fuel expenses, operational and maintenance costs, and decommissioning expenditures. Key challenges in implementing these reactors within ship designs are scrutinized, including considerations of safety, location, and refueling intervals.

Subsequently, the study investigates the intricate relationship between vessel speed and economic factors such as income, operational costs, and freight rates in liner shipping. Operational costs, especially fuel expenses, are found to significantly impact speed-dependent factors.

Concurrently, the impact of speed on hull shape and propulsors is evaluated, revealing a proportional increase in wave-making resistance at higher speeds and necessitating a reevaluation of power estimation methodologies.

The literature study is concluded with an assessment of three types of propulsors, where conventional propellers emerge as the preferred choice due to their efficiency, power range, and scalability.

The research then starts with the economic speed determination process, vital in shaping the vessel's design. This involves constructing a resistance curve based on a volume-scaled high-speed model vessel and factoring in components like CAPEX, OPEX, voyage costs, and freight rates. The study highlights the significant influence of freight rates on speed for all cases and underscores the viability of nuclear-powered vessels in achieving higher economic speeds due to lower fuel costs, especially over extended service lives.

With these foundational insights, the design process is initiated, emphasizing the optimal balance between speed, capacity, and real-world constraints. A scaled-down version of the nuclear concept vessel is developed, demonstrating a decrease in resistance while adhering to stability criteria. The resulting nuclear vessel design showcases a streamlined hull shape, minimal general arrangement alterations, and enhanced stability, with a notable preference for a three-propeller layout to optimize performance.

In conclusion, this study presents a concept design for a 20,000 TEU nuclear container vessel that achieves an increased economic speed, leading to design refinements in hull shape and propulsors. The research underscores the viability of nuclear propulsion in enhancing the efficiency of container shipping, providing valuable insights for future innovations in maritime transportation.

A significant decrease in greenhouse gas emissions can be achieved by including a prediction of future power consumption in the control of ships’ power plants during transits. Moreover, including a prediction of power consumption in the Energy Management System (EMS) during Dynamic Positioning (DP) operations can also contribute to a reduction in greenhouse gas emissions. However, predictions of future power consumption for DP operations, as well as its implementation in an EMS, have not been investigated widely, since this is a complex task for a relatively specific application. This research aims to investigate how power consumption during DP operations can most accurately be predicted for near-future and far-future, within reduced computational requirements for real-time applications.

In this research, six different approaches for power consumption prediction are investigated. These approaches can be categorized into projection models, which determine the power consumption independent of time based on the environmental conditions, and forecast models, which rely on the recent past behaviour of the system.
The four projection models consist of two Physical Models (PMs), a Data-Driven Model (DDM), and a hybrid model. The first PM is the static model, in which the environmental loads are directly compensated by the thrusters, hence the ship is assumed not to move. The second PM is the dynamic model, in which the motions of the ship are also modelled. Then, the DDM projection is based on Kernel Regularized Least Squares (KRLS) to capture the nonlinear relation between environmental conditions and power consumption based on historical data. Lastly, the hybrid projection model is an integration of the dynamic model in the DDM.
Afterwards, two forecast models are developed, being one DDM and one hybrid model. The DDM forecast is based on a combination between KRLS and Time Series (TS) forecasting. The hybrid forecast is an integration of the dynamic model in the DDM forecast.

Simulations are performed for each model using a data set provided by RH Marine. The DDMs show the most accurate results, taking into account the required computational effort. The results show that the forecast model, using the combination between KRLS and TS, predicts the near-future at 1 s in the future with 2.8 % error, increasing to 6.9 % at 120 s in the future. Afterwards, the projection model, using merely KRLS, predicts the far-future up to the length of the operation horizon with an accuracy of 11.2 %, based on the weather forecast. This multi-horizon prediction of power consumption can enable the EMS to make accurate short-term decisions in the control of the power plant and to define optimal scheduling of the power plant components over the
complete horizon of the DP operation.

Due to the expected increase in coastal replenishment along the Dutch coastline, and the need to decrease pollutant emissions in the Netherlands and worldwide, the Autonomous Low Energy Replenishment Dredger (ALERD) is developed. The ALERD is a sustainable and cost-effective solution to perform coastal replenishment work along the Dutch coastline and will be used for submerged dredging operating fully electric. The ALERD is modelled as an underwater vehicle in six degrees of freedom, from which the forward speed, the depth, and the pitch angle are controlled using motion controllers. The ALERD is the successor of the Autonomous Underwater Maintenance Dredger (AUMD), for which it is shown that the power for propulsion can be reduced with 55%, and the power required for the dredging pumps can be reduced with 80%, due to the submerged operations. A simulation model is used to determine the required power for stability and buoyancy control of the ALERD, since this was up to this point still unknown. To be a cost-effective solution, the energy consumption for motion control should be minimized. Traditional motion control methods such as proportional-integral-derivative (PID) control are widely used for controlling underwater vehicles. The more advanced motion control method Model Predictive Control (MPC) is seen as a more promising motion control method, in terms of both trajectory-tracking and minimizing the control effort. A Model Predictive Control strategy is developed and used to minimize the energy consumption of the ALERD for stability and buoyancy control. It is shown that MPC indeed outperforms PID control on tracking the desired reference signal, while minimizing the control effort and thus the corresponding required energy. A sensitivity analysis is done using Monte Carlo Simulations, to show the effect of modelling uncertainties on the outcomes of the simulation model. There is a minimum variation in the outcomes, considering the modelling uncertainties. MPC is better capable of handling with modelling uncertainties compared to PID control, in terms of trajectory-tracking and minimizing the corresponding energy requirements. The MPC controlled ALERD is compared with the PID controlled ALERD, and a conventional dredger, and it is shown that for a similar operational profile, the MPC controlled ALERD is the most energy efficient solution. The results from the simulation model still show significant advantages of submerged dredging compared to conventional dredging, even when considering the energy demand for stability and buoyancy control, based on the used operational profile.

The characteristics of a metal supported solid oxide fuel cell on methanol is analysed in as the power generator in a balance of plant consisting out of a reformer, combuster, heaters, pumps, turbines and tubes. The system is reviewed on performance regarding efficiency, power density, fuel utilization and viability for marine applications.

This research was performed with the goal of giving insight if the Rijksrederij is able to operate part of their fleet on renewable methanol and fuel cells, in order to work towards their goal of operating with net zero CO2 emissions by 2030. This prompted a research question that focussed on both the renewable methanol supply and the technical implementation on board of some of the ships operated by the Rijksrederij.
First, multiple possible pathways for renewably producing methanol were considered. Three main pathways were identified: two of which using waste biomass, one using recycled CO2 from on-board carbon capture. Green hydrogen could be provided using excess wind energy from Rijkswaterstaat’s own wind parks. In a later stage, it was found that a combination of biomass derived CO2 and recycled CO2 would be most beneficial to use in the methanol production process, by hydrogenating the CO2 with the beforementioned green hydrogen. However, this process resulted in net well-to-tank CO2 emissions.
To gain insight in all necessary components, a literature study was performed on maritime fuel cell systems and methanol reformers. Next, a model based on these systems was constructed that could be used in two ways: to aid in selecting specific systems and tank dimensions to be installed on board of ships, and to calculate tank-to-propeller CO2 emissions on both trip basis and yearly. Three different Rijksrederij ships were analysed using this model, and the spatial system integration on board was considered. In order to recycle the CO2 to produce green methanol, an on-board carbon capture system was needed and also modelled. The model is parametric in a way that allows for other ship types and fuel cell related systems to be used as input. In the end, the tank-to-propeller emissions for the three ship types were calculated, and these findings could be extended towards a larger part of the Rijksrederij fleet in order to calculate the entire well-to-propeller emissions of this fleet.
It was found that there were net positive emissions stemming from two sources: the aforementioned methanol production related emissions, and the slip stemming from uncaptured CO2 on board. Since not 100% of all CO2 could be captured on board, this also results in a gap in available CO2 for methanol production. In this sense, the production CO2 gap and the net well-to-tank emissions go hand in hand, and eliminating the net emissions (by capturing CO2 elsewhere, or improving the capture rate) also reduces the production gap. To achieve this, more research will be necessary.

The maritime sector faces major challenges to reduce its impact on global warming. The use of methanol as a fuel alternative is considered one of the more promising options to be implemented in a relatively short to medium time frame; based on the potential availability, emission reduction, energy density, potential to be synthetically produced, scalability of production, and its implementation on board ships (both new build and retrofitted).

This report investigates potential improvements of the injection system, to achieve complete evaporation in the air inlet of a port-fuel injection engine to avoid wall-wetting of the scavenger air receiver and inlet valve. As a result, the methanol-air mixture in the cylinder would become more homogeneous and able to provide 100% of the rated engine power. Earlier research indicated that the wall-wetting fuel film and its evaporation rate directly affect the air-fuel ratio of the in-cylinder mixture, stability of the combustion process, and overall engine performance. The study includes the development of an injection model simulating low-pressure port-fuel injection, similar to the system fitted on our Caterpillar test engine, and the development of a single-droplet evaporation model to gain inside into the evaporation process of 100% methanol.

Based on the performed experimental research, we conclude the average droplet size ranges between 100 and 120 μm. The average droplet speed was determined at ±35 m/s and the spray angle at 20°. At room temperature and pressure, the injection spray ended against the back-glass of the evaporation chamber, indicating almost none of the ethanol evaporates under these conditions. The injection length exceeds at least ±40 cm at atmospheric temperature and pressure, which is in line with the results of the single-droplet evaporation model.

Global warming is a topic of major concern the last decade and for reason the IMO adopted a strategy to reduce the emissions of greenhouse gasses of vessels. In order to meet the IMO requirements ships propulsion systems need to become more sustainable. An option to reduce emission is the implementation of fuel cells running on hydrogen together with batteries. Since hydrogen cannot be stored into conventional fuel tanks different fuel tank options are investigated, which led to the use of cryogenic liquid hydrogen storage tanks.
During the research a case study was preformed for the Pioneering Spirit. The first step in the designing process is investigating the operational profile to get a better understanding of the projects done and the corresponding power demand and to see how the operational profile influences the power demand of the ship.

After investigating the operational profile and its influence on the power demand of the ship a design methodology was written to help the user find an optimal solution for the new hybrid propulsion system. This methodology contains three parts: data importing, solution generation and new system specifications.
In the first part data will be imported and processed to find the power demand during a project. Subsequently, a range of fuel cell capacities will be determine over which solutions will be generated in part two.
The second part of the methodology contains three steps. During the first step solutions will be generated over the range of fuel cell capacities determined in the first part. This first step will be iterated for different battery capacities. After generating solutions in the first step in the second step suitable solutions will be defined. These solutions will be compared in the last step to find an optimal solution.
For the optimal solution, the third part of the methodology will calculate the new system specifications.

In the modern world, environmental concerns arise due to an increase in the green house gas (GHG) emissions of the shipping industry; in 2015, 2,5% of global GHG emissions came from the shipping industry alone. Measures must be set in place to reduce the future emissions. One way to reduce emissions is by imposing the Energy Efficiency Design Index (EEDI). This is a measure to define the ratio between the CO2-production and the cargo capacity and speed of a ship. In other words, this ratio defines the environmental cost over societal benefit of a ship. The International Maritime Organisation wants to have a set requirement on the EEDI of new ships and preferably reduce this for existing ships. One way to reduce the EEDI is by reducing the installed engine power of the ship. One risk is that the ship might then become underpowered when it sails in adverse weather. The underpowering of ships could lead to safety hazards for the passengers and crew. For that matter, this thesis will investigate whether the ocean-going chemical tanker 'Castillo de Tebra' is underpowered when sailing in large waves. Specifically, the effect of the waves on the inflow velocity of the propeller will be looked at and how this affects the propulsive performance of the vessel.
An extensive literature review was carried out in order to find out what the state-of-the-art is within the determination of ship propulsion in waves. This has been divided into three separate subjects, namely wave excitation, propeller and engine operating in waves and finally manoeuvring and seakeeping. When determining the forces that occur on a ship when it advances in waves, most methods use potential flow as the results are reliable and have low time effort. Determining propeller performance when the full wake distribution is known can also be done using potential flow methods. Basic open-water characteristics are a valid alternative as well. CFD can be used for both wave excitation and propeller performance calculations, but this is time consuming and computationally complex. When simulating manoeuvring and seakeeping behaviour of ships, two-time scale methods or unified methods are mainly used.
For the research part of this thesis, numerical simulations were performed to determine the change of inflow velocity at the propeller plane for a large range of wave frequencies and wave directions, for a vessel having a forward speed. This velocity change was used to determine what the thrust and torque generation of the propeller is in waves. The engine operating envelope and ship thrust envelope were used to check whether the engine has enough power to provide the torque that the propeller generates and whether the ship has enough thrust availability. Frequency-domain results were transformed into time records for irregular waves using the JONSWAP wave spectrum and a cosine funtion. It was concluded that the ship was underpowered in adverse weather conditions, when an instant control system was assumed that inject enough fuel instantly to keep the engine at the rated speed when it needs to deliver more power. It was also assumed that the ship speed was kept at the design speed. In reality, voluntary and involuntary speed loss will occur when a ship sails in bad weather. Voluntary in the form of manual speed decrease by the captain and involuntary in the form of added resistance causing the ship to reduce in speed. A number of solutions are finally presented in this thesis to omit engine overloading in adverse weather.

The shipping industry is forced to reduce its emissions and underwater radiated noise in order to decrease the impact on the environment and limit global warming. Moreover, a low acoustic signature can be lifesaving for a navy ship, especially during submarine on mine threats. To be able to operate as flexible as possible under these threats, a flexible propulsion plant is required. A diesel engine with a controllable pitch propeller (CPP) is contributing to this. A method to reduce the emissions and noise of such a plant is to improve the control strategy. Often this is tested with numerical models. However, frequently they contain many simplifications of reality, for example, the neglection of several hydrodynamic effects. Hardware In the Loop (HIL) takes these effects into account by replacing a software part of the model with a hardware component. In this research, the CPP is the scaled hardware part. A feasibility study is performed to determine whether a propeller open water HIL setup can be used to simulate the dynamic behaviour of the propulsion plant. Therefore, a comparison is made between full and model scale numerical simulation of a diesel engine with a CPP controlled by adaptive pitch control (APC). To reduce the pitch actuations with the APC strategy a Kalman filterwith deadband is implemented. Full-scale simulations with irregular waves demonstrated that the pitch actuations could be reduced during acceleration and at a constant speed. The validated full-scale model is Froude scaled and implemented in a model of the open water HIL setup. The results of the full and model scale simulations are very similar. Thus, the HIL setup can be used to simulate the dynamic behaviour of a propulsion plant. However, the hardware limitations such as the backlash in the CPP blades, the low sample rate of the actual pitch and the Froude dissimilarity of the acceleration of the towing tank need to be resolved to ensure the scaled simulations are representative for the actual, full scale, vessel. Due to these limitations, it is not possible to use the setup at this moment to perform experiments and improve novel control strategies. If these physical limitations of the current HIL setup are overcome, the effect of the propeller and the pitch control strategy during turns can be investigated by performing experiments with oblique inflow.

Ammonia fuel has been widely considered as an attractive solution for reducing the green house gas emissions over recent years. Adapting ammonia as fuel on ships would highly reduce the carbon footprint of international shipping and off-shore transportation. Among the different systems currently under development for carbon-free power production in the near future, the combined-cycle gas turbine system stands out for its relatively high system efficiency and a potential for running on pure ammonia fuel while maintaining a low level of NOx emission. This thesis project puts a sight on a special design of this type of COGAS power system and tries to adapt it for maritime usage onboard future ships. Previous researches have pointed out the key design features of the ammonia COGAS power system being running under a high fuel-air ratio with a cooling method based on EGR technology and cracking the additional ammonia fuel into hydrogen in the gas turbine system, then this created hydrogen concentration could be used for re-heating the exhaust before it is used by the combined steam cycle. However, current understanding of this type of COGAS system is still limited under static analysis and designed working points. This thesis project tries to provide a basic view on the off-design performance and dynamic behaviors of this COGAS system, and examines if this system is still able to maintain a low level NOx emission under such working conditions. This thesis project combines a dynamic model of an ammonia gas turbine and a chemical thermodynamic model for simulating the chemical behavior of the work fluid inside the gas turbine system. It is found that the fuel-air equivalence ratio of the gas turbine needs to be designed at a high value to ensure the flammability of the hydrogen consisting exhaust in the re-heating process. A very low NOx emission is observed in the gas turbine exhaust under an assumption of complete chemical reactions. The final NOx emission of the COGAS system is found to be within the EEDI Tier III limitation under both rated and part-load working conditions. The thermal efficiency of the gas turbine is relatively low due to the high equivalence ratio, while a system efficiency comparable with current oil-fueled COGAS power system is able to be expected for the full system of ammonia COGAS. On the phase of dynamic analysis, this project has concluded that traditional fuel control method for controlling gas turbine power generation is not adaptable to gas turbine systems working at fuel-rich conditions. A non-linear behavior is observed due to this high equivalence ratio. This thesis provides a new controlling method with controlling both the fuel injection ratio and the EGR ratio with an additional feedback controlling system attached to the original feed-forward system of the fuel control. Basic tests shows that such method is able to generate a dynamic output with the correct tendency. This thesis project also observes a high sensitivity of NOx emission with the presence of additional oxygen in the exhaust under a complete chemical reaction. In this thesis project it is found that the considered ammonia COGAS system maintains the advantage of traditional COGAS power systems and a is able to take an advantage in comparing with medium-speed diesel systems under an ammonia economy. Power output of the ammonia gas turbine is able to be controlled with a combination of fuel control and EGR control. A low NOx emission within the limit of EEDI Tier III is observed under both rated and part-loading conditions of the power system, but this is achieved with the assumption of a complete chemical reaction. Whether this assumption is adaptable to maritime scaled ammonia gas turbine system requires further kinetic analysis on the combustion process and further research efforts in the designing of the combustor system.

The International Maritime Organisation (IMO) has set the goal to reduce the total annual greenhouse gas emissions from international shipping by at least 50% by 2050 compared to 2008. For this reason, shipowners will have to innovate the drive-trains and energy systems of their vessels to reduce harmfull emissions. To achieve this goal, solutions must be found to store large amounts of cleen energy on board of ships and convert the chemical energy in an efficient way with these drive-trains. Hydrogen is considered as a promising solution for this. However, storing hydrogen is complicated and requires much volume. To overcome this barrier, hydrogen can be stored in dense hydrogen carriers (DHCs). This thesis will perform a technical and economical feasibility study of dense hydrogen carriers as a fuel to power a semi-submersible offshore crane vessel. The Sleipnir, the largest crane ship in the world, is the main subject of this thesis. The objective is to evaluate the technical and economic feasibility of hydrogen based fuels for semi-submersible offshore crane vessels and their impact on the drive-train design. This will be done by designing a new drive-train that can deliver 6.5MWelectricity to power the ship’s hotel load.

Submarines face an ongoing (technical) battle to improve the operational effectiveness by increasing the submerged endurance and range. Installing lithium-ion batteries on new or refitted diesel-electric submarines has become increasingly interesting based on their relatively high energy density and specific energy. The characteristics compared to the currently implemented lead-acid batteries are known, meaning that the implementation of lithium-ion batteries on submarines can increase the submerged range and endurance based on their better specifications. Additionally, lithium-ion batteries require less maintenance and provide a relatively longer life expectancy compared to lead-acid batteries. However, lithium-ion batteries can develop a thermal runaway: a process which exponentially generates heat, leading to the risk of an explosion and fire. A thermal runaway can be initiated based on internal failure mechanisms and external causes, such as exceeding critical temperature limits. Understanding of the thermal behaviour of lithium-ion batteries is essential to reduce the probability of a thermal runaway. The probability of initiating a thermal runaway can be further reduced by auxiliary systems such as a cooling system and a battery management system. The main objective of this research is therefore to investigate the implications on preliminary submarine system design based on the thermal behaviour of lithium-ion batteries and to quantify the thermal behaviour and design implications. The relevance is that by quantifying the thermal behaviour, the cell temperatures can be estimated. As a consequence, awareness of the risk of a thermal runaway is established, while at the same time input for the dimensioning of a cooling system is provided. An analysis has been performed concerning the safety of lithium-ion batteries. The causes, the characteristics and the prevention methods regarding a thermal runaway have been studied in this research. The four stages of a thermal runaway are discussed, as well as the generation of toxic and flammable gasses. Moreover, the sources of heat generation in a lithium-ion cell have been described. The heat generation typically consists of reversible and irreversible heat components, of which the relative contributions have been described based on the charge or discharge rate. To support preliminary submarine design, a thermal model of a lithium-ion battery module has been created. The first model that has been created describes the electric behaviour of a lithium-ion battery cell that is typically implemented in marine applications. EST-Floattech has provided technical specifications of the lithium-ion pouch cell that is implemented in their modules. The second model determines the generated heat based on the electrical model and cell specific properties. The third model simulates a lithium-ion battery module, where heat is generated by multiple cells and heat transfer rates with the surroundings are modelled. A lumped thermal capacity approach has been implemented and cooling is modelled to provide insight in typical cooling rates regarding thermal management. Conclusions have been drawn regarding the temperatures of the cells in the module based on three operational profiles. Based on a submerged sprint, C-rates up to 1.0C can be sustained without cooling while remaining below the critical temperature limit of 55°C. For consecutive cycles during a covert transit or covert surveillance, cooling is typically necessary. Only at C-rates below 0.3C a covert transit can be sustained. Typical cooling rates vary between 60 W and 185 W, where the effects of cooling are most significant for covert transit and covert surveillance. Module optimisation provides increased cooling rates while increasing the energy density and specific energy. This results in a decreased mass and volume of the module, resulting in a significant amount of extra space in the entire battery system on board of a submarine. The largest improvement in thermal management can be realised by choosing the right conductive filler. Moreover, the cooling capacity has a significant influence on the cell temperatures. Cell temperatures remain relatively constant after the fourth cell in a row, meaning that modules are typically not limited by the number of cells.

In recent years, ships are expected to improve energy efficiency and reduce carbon emissions. For naval vessels, it is important to be able to maintain their mission profile. It is therefore required to provide real-time advice to the ship’s crew on the optimal speed and propulsion mode settings that include the actual environmental conditions. This paper proposes a novel machine learning approach to establish the ship’s fuel consumption per mile for the actual environmental conditions and develop fuel consumption curves for the various propulsion configurations. The proposed approach uses a multi-layer perceptron (MLP) model to establish the ocean parameters based on the own ship data, with an accuracy of 4.150 %. Using these ocean parameters combined with the own ship data, the fuel per mile is predicted and fuel consumption curves are established using an MLP-model, with an accuracy of 1.551 %. This thesis shows that the proposed approach makes it possible to help a ship’s crew make well informed decisions to reduce their CO2 emissions in real time while still meeting their mission profile. The proposed approach is especially useful for military operators since there is no need for external data sources. Further research is identified to optimize the proposed approach using a dataset containing a higher variety and number of environmental conditions and propulsion modes to improve and validate the fuel consumption curves for the entire spectrum of speeds, environmental conditions and propulsion modes.