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.

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.

To reduce the climate change impact of shipping and retain compliance with increasingly strict emission regulations, alternative fuels are required. Methanol is expected to be one of the renewable alternatives. However, it evaporates easily compared to for example Diesel and its vapours are toxic and flammable. Regulations prescribe the use of 10m radius hazardous areas around the vent mast connected to the ship's tank. These areas pose stringent limitations on the use of a ship. In this context, knowledge is lacking on the actual risks induced by possible outflows, let alone on outflow mitigation measures. In this research an analytical thermodynamical model of a ship's methanol fuel tank is developed, it is analysed what appropriate safety measures are and what their effectiveness is. The thermodynamical phenomena inside a ship's tank are inventoried from literature and on a selection of these a model is derived. With the model, outflow values of methanol mass with and without outflow mitigation measures are simulated for various scenarios and tank sizes. The scenarios are (1) heating during the transition from night to day or (2) due to a fire and (3) the most critical post bunker situation. The latter occurs after the ship's tank is filled for the first time prior to which no methanol vapours are present. It is found that outflow values correspond to a hazardous area size much smaller than the prescribed 10m except for the fire scenario. However, mitigating the outflow with a PRV and with locating the tank floor in contact with the seawater is found to be very effective. With application of mitigation measures, only the most critical post bunker situation results in a hazardous area of larger than 1m, being 1.17m. Assessment of the model accuracy is limited to the presented scenarios, limiting the model applicability to the ranges in which the parameters are varied within this research.

Environmental and operational challenges associated with an excessive fuel consumption have led to the need for future naval vessels to be less dependent on fossil fuels. The chosen configuration is combined diesel-electric and diesel (CODLAD). However, there is a performance gap regarding the manoeuvrability between the previously implemented gas-turbine propulsion and the diesel-electric hybrid propulsion. In order to reduce this performance gap between a gas-turbine propulsion system and a diesel-eclectic propulsion system a new optimized control system needs to be developed. Adaptive pitch control avoids the angle of attack peak, reducing the torque peak that can potentially overload the diesel engine. Adaptive pitch control is the only control strategy that operates at a low angle of attack, and therefore is less perceptible for cavitation. However this peak in angle of attack is responsible for the peak in thrust. Adaptive pitch control therefore needs large shaft speed fluctuations to be able to create a large thrust. Adaptive pitch control is therefore either slow or forces the diesel engine to rapidly make large changes in its shaft speed. The rapid changes in shaft speed could increase the amount of wear inside the engine, reducing the time between maintenance. During the simulations torque control for the diesel engine performs extremely well during acceleration. Using torque control for the diesel engine the static power distribution of the propeller load was varied. During these variations it was concluded that a large acceleration can be achieved with a heavy loading on the diesel engine in steady state, supported by a large torque production during acceleration by the induction machine. A heavy matching of the diesel engine was possible because the diesel engine only produced the power needed for the steady state propeller power as matched via the combinator. The induction machine is made responsible for keeping the speed and coping with disturbances. The induction machine is inherently more suited than the diesel engine, due to its fast response as well as it being able to produce full torque or maximum power without any negative adverse effects. However torque control is not available from manufacturers. This research includes a novel implementation of a dynamic power split, which produced very promising results. The dynamic power split uses the diesel engine with speed control parallel with the electric drive in dynamic torque control. The dynamic torque control for the induction machine allow for optimal usage of the inherent characteristics of the electrical machine. Using dynamic torque control the induction machine is responsible for the high frequency load changes such as disturbances as well as the first part of the acceleration. The diesel engine governed by a slower integral dominated PI controller accounts for the low frequency load changes, including the higher load at a new steady sate. The diesel engine with speed control parallel with the electric drive in dynamic torque control produces excellent acceleration characteristics, making it a viable option to improve the acceleration characteristics of a diesel-electric hybrid system.

Emission regulations applied to marine industry for amongst others the propulsion system of a vessel are becoming stricter due to governmental agreements to lower the greenhouse gas emissions. Engine manufactures are enhancing their engine designs to reduce the engine fuel consumption, which is commonly done by implementing a turbocharger to downsize the engine. One large drawback which comes with a turbocharged engine is the low torque development for the low to mid engine speed range due to limitations set to prevent unstable turbocharger phenomena. Moreover, the engine is not able to follow the power request almost instantaneously due to a time delay between the engine and turbocharger response. Formula One engineers close this gap by introducing an integrated electric machine into the turbocharger structure (hybrid electric turbocharger) to, first, take power out from the turbocharger to increase the system efficiency, and second by assisting the turbocharger to improve the engine power delivery response. However, the understanding of the effects of a hybrid electric turbocharger on both the system efficiency as well as the engine loading capability is lacking. One turbocharger limit, the compressor surge, is not concerned in most literature what rises the need for further research up to which extent the engine can be assisted with the hybrid electric turbocharger. In this work, the effect of taking power from the turbocharger to increase the system efficiency, called turbocompounding, is investigated. Turbocharger assistance is investigated for both steady state as well as dynamic operation. The effect of assisting the turbocharger for steady state operation is investigated to increase the engine’s operating envelope. Dynamic operation comprises the investigating up to which extent the assisting mode improves the dual fuel engine’s loading capability for four types of engine loading. These types of engine loading are: one instant load step, three consecutive load steps from 0 - 100% load, a load ramp and, last, a sinusoidal engine loading. This has been done with a simulation-based study wherein a mean value dual fuel engine model is composed based on merging two available mean value engine models, after which it is verified and validated. Thereafter power take in/out together with an air excess ratio control strategy is included by means of adding/taking torque to/from the turbocharger shaft and limiting it with eight boundary controllers to avoid impractical situations. With turbocompounding the system efficiency can be increased at the expense of a deteriorated gas exchange and increased thermal loading of the engine. The maximum quantity of recovered energy to be obtained, requires a hybrid electric turbocharger which replaces a waste gated turbocharger instead of a non-waste gated single stage turbocharger. Taking power from the turbocharger lowers the power available for the compressor which leads to reduced inlet receiver pressure and corresponding lowering of the air excess ratio and deterioration of the scavenging process. Assisting the turbocharger for steady state operation leads to a smaller operating envelope due to the limitation of compressor surge. Combining turbocharger assistance with gas exchange bypass valves, to avoid compressor surge, results in a rise of the low speed torque output up to an almost constant engine torque output. The system efficiency can be improved for the low speed region when the turbocharger is assisted in combination with the gas exchange valves. The load step capability, found by limiting the minimum air excess ratio during the load step event, cannot be increased with turbocharger assistance which starts to speed up the turbocharger immediately after the load step is applied to the engine. However, the recovery time needed before a second load step can be taken, is reduced with turbocharger assistance compared to the baseline engine. When the turbocharger assistance starts to speed up the turbocharger a couple of seconds before the load is applied, the load step capability can be improved. A load ramp can be taken in a shorter period of time with turbocharger assistance enabled. For cyclic loading, the hybrid electric turbocharger operates in turbocompounding mode for the lower load frequencies, and assistance is used for the higher load frequencies. With turbocharger assistance the air excess ratio does follow the sinusoidal engine load while the air excess ratio of the non-assisted engine always lags due to the turbocharger lag. Further research should be done with regard to a hybrid electric turbocharger for the natural gas combustion of the dual fuel engine. Using the engine speed drop should be implemented as limitation for the loading capability determination instead of the minimum allowable air excess ratio applied in this thesis.

In the context of this thesis, the effect of various diesel-methanol blends in a diesel engine compared to conventional marine diesel oil is investigated by experiments and in-cylinder simulations. The main differences obtained between diesel and methanol are the lower heating value, heat of vaporization and cetane number. During the experiments, the engine was not able to run on M20 at loads lower than 153 [kW]. Pressure signal comparison between the cylinders showed that cylinder one shows better ignition properties for methanol operation compared to cylinder two, three and four. Higher COV's for IMEP and maximum pressure were obtained by methanol blends. Experiments with F76, M10 and M20 fuel have shown that methanol blends increase the specific fuel consumption and slightly decrease the engine efficiency. Specific NOx emissions decreased with 2.9 up to 14.2 [%] by methanol blends compared to F76. Due to the increased fuel consumption, the CO2 emissions hardly reduced. Exhaust gas temperatures and CO emissions seems to decrease. The ignition delay of methanol blends increased up to 8 [degrees CA] for M20 while remaining the brake power constant. Moreover, the combustion duration and air excess ratio decreased by using methanol blends. A single droplet evaporation model is built to simulate the evaporation heat losses for methanol fuel during the in-cylinder process. Methanol has a longer evaporation time which is a disadvantage for diesel engine applications. By using the single droplet evaporation model combined with an injection model calibrated for dual fuel direct injection, the fuel spray evaporation heat is calculated for implementation in the single zone model. The results are calibrated by using the droplet diameter as a variable. In this way, the evaporation heat required for evaporation of methanol is simulated in the dual fuel single zone model. Heat release analysis shows that the premixed combustion phase of methanol blends is dominant compared to F76, while the diffusive combustion phase significantly reduces. For methanol blends, the residence time at high temperatures is lower due to the decreased combustion duration and elongated ignition delay. Unfortunately, the results from the dual fuel single zone model are strongly dependent on the position of the pressure signal. Results for the temperature of the mean cylinder two, three and four were not in line with the expectations. Cylinder one showed smoother heat release curves and its temperature result was in line with the expectations based on the exhaust gas temperature. More research to the effects of the fuel injectors on the heat release of methanol/diesel blends is recommended.

Hydrogen enables renewable energy storage, and hydrogen carriers can allow easier transportation. This research was initiated to get more insight into transporting renewable hydrogen carriers (RHCs) by ship, which is one of the transportation options. The research was conducted in three steps. First, a system description with a literature study was made to select suitable RHCs, based on the production, and the performance as a hydrogen carrier. Secondly, a basic model for three transportation cases was made. Thirdly, a more detailed model was created to evaluate different transportation options. The four most attractive RHCs to be shipped are the synthetically produced: methanol, liquefied natural gas, liquid hydrogen, and liquid ammonia. In the model, short and long term options are evaluated for the same, mild and strict regulations compared to today. The following statements can be made, based on the results of the second model: • Ammonia is best suited in a scenario with strict regulation compared to today. Ammonia has a noncarbon nature; therefore, it is the most promising option in the long term. • Methanol is best suited for small scale transportation in the short and long term, in which the same regulations are active. The storage of methanol on board of the ship is relatively simple and it has a relatively high hydrogen density. • LSNG is best suited for large scale transportation in which the same regulations are active. LSNG has the highest hydrogen density of the discussed RHCs. The advantage of SNG is that during the reconversion to hydrogen, extra hydrogen will be produced because of the added steam, during steam methane reforming (SMR). • Liquid hydrogen is from a shipping point of view not the most suited for the transport of hydrogen, due to its low volumetric density and complex storage. Shipping liquid hydrogen has the advantage that it reduces extra conversion steps in other parts of the supply chain. Shipping RHCs and using the carriers as a fuel is an option which involves higher cost compared to current fossil fuel options. This relatively high share of fuel expenses using RHCs will make efficient powertrains relatively more attractive because it enables higher fuel cost savings. The most attractive engine configurations are a two-stroke internal combustion engine with a mechanical powertrain and a SOFC with a battery in an electric powertrain. The last option is especially promising for the long term, because of the technologic developments and increasing regulations in shipping. Overall the results indicate that shipping NH3 and using the carrier as a fuel is the most promising option for the transport of RHCs by ship. This research and constructed models can be used as a tool to evaluate different transportation options. However, used values are based on various sources and their corresponding assumptions, which can change significantly in the future.

The growth of the cruise industry throughout recent years and the changing public opinion on cruise ships has led to increasing concerns regarding the impact cruise vessels have on the world’s climate and environ- ment. Cruise passengers prefer not to be related with heavy polluting vessels. In fact, trends like responsible tourism and sustainable travel are increasing, especially among younger generations. In order to maintain a viable business model, cruise operators are compelled to consider exploring new energy sources and energy carriers to power their cruise vessels. Alternative carbon-neutral fuels are found to be a potential solution. As such, this research aims to evaluate the viability of possible alternative carbon-neutral fuels on board cruise ships.

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.

The maritime sector is important for the facilitation and growth of global trade. Currently, about 90% of the goods are transported by ships and as a result, the number of ships has risen, increasing the emissions related to shipping. Pollution caused by exhaust gas, especially the sulphur oxide emission, from marine diesel engines has become a global concern in recent years. Therefore, the International Maritime Organisation limited marine fuel sulphur content in both Emission Control Areas to 0.1%w/w since 2015 and globally to 0.5%w/w since January 1st , 2020. It is anticipated, that the newly implemented IMO regulations will help to mitigate negative impact of ship emissions on public health and the environment in the coastal areas. The wet scrubber system is a reliable technology for flue gas desulphurisation in marine applications and can achieve a sulphur dioxide removal efficiency of 98%. The operating costs are low, however the capital cost for installation are high and a scrubber system requires space for installation while maintaining ship’s stability. Wet scrubber systems operating in a closed loop and using caustic soda may operate without discharge to the sea and thus are allowed to operate in ports. The use of caustic soda also makes it possible to use the scrubber in areas with low seawater alkalinity. However, scrubber systems generally operate at 100%, even when the engine operates at lowload. This results in an increase of the fuel consumption and carbon dioxide emissions. Themain objectives of this research are to examine the influence of water evaporation on the sulphur dioxide removal efficiency and the (response of the scrubber) effect of dynamic loads on the scrubber efficiency. A dynamic model of a closed loop wet scrubber operating with fresh water and caustic soda also known as sodium hydroxide was created and verified. The scrubber model consists of three resistance elements, namely the venturi scrubber, the tower scrubber with a packed bed and the demister and two volume elements (lower and upper) to connect the resistance elements. The absorption of SO2 is mainly taking place in the packed bed and the two phase flow of exhaust gas and scrubbing liquid was modelled in this section. The Nerst film theory was used and extended to a two film theory in which the exhaust gas and scrubbing liquid phases come into contact through an interface and exchange both heat and mass. The gas flow in the packed bed could be modelled with a combination of resistance and volume elements as this phase is compressible. The liquid flow and liquid film thickness in the packed bed were modelled based on the conservation of mass and the liquid holdup theory developed by Billet and Schultes. A feedback control system controls the scrubbing liquid flow based on the sulphur dioxide to carbon dioxide ratio. The system includes a time constant to account for the inertia of the scrubber’s pump and pipe system. The verified model was integrated with engine data and used to run several static and dynamic simulations. The inclusion of evaporation in the packed bed leads to an increase of the scrubber efficiency in all engine loads. The extra vapour added dilutes the gas phase and reduces the mass fraction of sulphur dioxide. When evaporation is included in the analysis, the sulphur dioxide to carbon dioxide ratio leaving the scrubber is 1.88, equal to a fuel sulphur content of 0.043% on a mass base (from 3.5% in the fuel) for 100% engine load. When evaporation is not included in the analysis the previous values are 2.3 and 0.053% respectively. To increase the precision concerning the amount of water that evaporates, a higher discretisation of the packed bed is required. High engine load fluctuations and/or high input frequencies lead to overshoots and higher liquid supply, in order to keep the scrubber system efficient. In the transition from 25% MCR to 100% MCR the liquid supply exceeds the nominal value of 94 kilogram per second by by 5.3 kilogram per second (or by 5.6%). In the transition between 75%MCR to 100%MCR, for the frequency of 50 seconds the liquid supply is equal to 92.9 kilogramper second. Increasing the input frequency 5 times results in an increase of the liquid supply to 96.1 kilogram per second. The sulphur dioxide to carbon dioxide ratio leaving the scrubber was always below the ECA sulphur limit and was fluctuating around the set point, but most of the time below it. A combination of feed forward and feedback and/or a more advanced control may result in a more stable control of the scrubber, but this has to be investigated. The model functions, but more research is required for the venturi and the demister models, but also for the packed bed model. In the venturi a three phase flow is required and in the demister an analytical and dimensional analysis is required. Also, the packed bed model needs to be further developed to include the condensation effect and a more precise approach for the liquid phase. Further research can be done on the integration of the model with a diesel engine and SCR model. Also, seawater can be examined as a scrubbing liquid as this may reduce the operational costs of the scrubber. Finally, because space requirements of the scrubber are high, a structured packed bed could be an alternative to the dumped and reduce the space occupied by the wet scrubber.

Carbon dioxide emission into the earth’s atmosphere by maritime activities are a concern for the people within and outside the industry. This is because of the environmental impacts that are caused by these greenhouse gas emissions which changes the very chemistry of this planet. These impacts can be mitigated by reducing the CO2 emissions which can be achieved by several design and/or operational means. Waste heat recovery (WHR) technology is one such means that is capable of reducing emissions. This is achieved by improving the overall fuel efficiency of marine engines which reduces the fuel consumption of the vessel. This improvement is realised by harnessing the heat energy that is expelled by the engine through waste heat sources such as exhaust gas, etc.  Organic Rankine cycle (ORC) is one of many WHR technologies that is capable of harnessing that waste heat energy from the fuel which cannot be utilised by the engine operation alone. ORC as a WHR system (WHRS) is widely implemented in land based applications due to its fluid choice flexibility, plant simplicity and net efficiency. However, it is rather new to the maritime industry because WHRS on-board ships are predominantly based on steam Rankine cycle or turbo-compounding. These systems have their own advantages but ORC-WHRS may outweigh them in certain applications on-board ships. This is especially for electrical power generation from low and medium temperature waste heat sources. However, ORC in marine application encounters challenges unlike seen in land based applications. These challenges are caused by the physical & geometrical constraints, operational profile of the vessel or uncertainties caused at sea.  In this thesis, the implementation of ORC-WHRS to marine engines for exhaust gas is investigated and studied to understand how such an application can be beneficial. Unlike steam Rankine cycle, an ORC system has flexibility in choosing an organic fluid that is suitable based on the application. This flexibility in fluid choices are confronted by the above mentioned maritime related challenges. Hence, a screening methodology is devised in this thesis that finds a suitable fluid based on the waste heat source profile and selection parameters. These selection parameters are necessary to filter out functioning organic fluids that can be limited due to the mentioned challenges. In this thesis, the power density of the ORC plant is the selection parameter used.As mentioned earlier, the ORC-WHRS may often be subjected to off-design conditions due to the operational profile of the vessel or by uncertainties at sea. Hence, off-design performance is analysed to study the ORC system when designed at several discrete engine load points. These analysis are carried out in plant models modified from an existing steam based dynamic model and developed into a simple-ORC and a recuperative-ORC dynamic plant models. Sensitivity analysis of these models are also performed to understand uncertainties in the model output corresponding to uncertainties in model input parameter. This analysis is followed by analysis of the dynamic behaviour of the ORC plant model to varying load step functions and step duration for plants designed at discrete engine load points.  This thesis can be extended, not only to study how ORC can be used to meet future regulations on CO2 emissions, but also on operability limitations imposed on ships. The fluid screening approach used here can also be modified based on parameters, such as toxicity, flammability, cost, specific power etc. This can present a realistic approach to an end product that can be safely and economically operated on board.

Keeping a submarine stable underwater is important to be able to execute missions. Therefore, one of the main systems on board of submarines is therefore the ballast trim system. This system is able to maintain the submarine balanced. There must be equilibrium in weight and buoyancy as well as in the trimming moment. This makes the ballast trim system a vital system on board of submarines. The world around us changes, causing new mission specifications and requirements. This results in a different operational profile than before, which has consequences for the ballast trim system. For example, for a modern submarine hovering is desired, resulting in a faster and more accurate ballast trim system. Therefore, the existing systems must be reconsidered for modern SSK submarine applications. Next to the changed environment, new technologies are available, which might be applicable for a modern SSK submarine. The main goals of this research are: give insight in the ballast trim system and see which technologies are best to use in the ballast trim system. The technologies are tested on the 4000 and 2000 ton BB2 submarine. In this research different empirical models were set up in order to simulate the behaviour of the different ballast trim systems. The results of these models are compared to each other based on energy, noise and redundancy. As an input, different mission profiles were made, which are likely to be executed by a modern SSK submarine. The ballast trim system was divided into three separate systems for the comparison, namely: trim, compensation and hover. From the simulation made there was seen which modelled solutions were the best capable to use as a ballast trim system. In this research also the second order effects of waves were included. There is seen from the simulation that it is possible to compensate for the motions due to these second order wave effects. The simulations also showed that a new technique, the so called ‘variable buoyancy system’ is very promising. With the results from this research it can be seen which system can be best used as ballast trim system for the three different tasks on board of the BB2 submarine. To maintain longitudinal equilibrium, it is best to use a centrifugal pump to transfer ballast water between tanks. To maintain balance between the weight and buoyancy forces of the submarine, it is best to use a plunger pump. It is also seen that a centrifugal pump in a system with a very large static head compared to dynamic head, is hard to operate and can even become incapable of expelling water from the tank. For hovering, a special dedicated system is needed. For the 4000 ton BB2 submarine, it is best to use a pre-pressurised tank to lose weight very fast in case of a change in seawater density. The 2000 ton BB2 submarine can use its snorkel mast to maintain equilibrium. For low frequency forces such as the second order forces due to waves, both studied BB2 submarines can use their snorkel mast to keep the submarine at depth.

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.

The activities of humans in the marine environment are on a steady rise; this trend follows the exposure of offshore structures and vessels to harsh environmental conditions. On the other hand, there is continuous demand for lighter, faster and more efficient vessels. Technological advancement in composite materials and better design methods invariably leads to more sophisticated computational tools. In these tools, the inherent flexibility of the structure is involved in the calculation of its loading and response – introducing the aspect of fluid-structure interaction. However, more than fluid-structure interaction, hydroelasticity which is a subset of fluid-structure interaction allows for deformation of the structures due to fluid. Current industry practice neglects these deformations and all structures are designed as rigid bodies. These practices lead to overestimation of the frequency which translates to the mass and how stiff the structure is. Design based on hydroelasticity allows for knowing the true behaviour of the structure; thus, a coupling of fluid and structure yields a true appreciation of these designs. The objective of this study is to formulate and solve analytically the coupling phenomenon behind fluid-structure interaction. An experiment designed by Lampros Rizos in 2016 which modelled fluid-structure interaction consisted of a set-up with a cylinder immersed in a larger cylindrical tank. The immersed cylinder having a flexible circular membrane (structure) located at its bottom. The cylinders were filled with non-viscous liquid and exhibited free surface. The designed experiment was decoupled and a systematic build up in understanding the dynamics of all components – structure and fluid were solved. Firstly, the dynamics of the structure when dry (In vacuo) was idealized in 2-D and 3-D. Secondly, the system was coupled and solved in 2-D and 3-D when structure is located at the top and bottom of a single cylinder individually. The use of a series solution: Fourier-Cosine and Fourier-Bessel series solutions were used for 2-D and 3-D cases respectively. Along with these series solutions, the fluid governing equations were employed to solve for the coupled frequencies. Lastly, the entire submerged structure was analysed and solved. The hydroelastic or coupled frequencies and vibration patterns are determined for lower angular and radial modes for which the influences of various parameters are investigated. A trend was observed – that for lower modes, the hydroelastic frequencies are lower than individual membrane natural frequencies at low frequencies. At higher frequencies, the coupling effects are larger making the coupled frequency higher than uncoupled frequencies. There is a strong relationship between the tension of the membrane and the hydroelastic frequencies. An increase in the tension causes an increase in the hydroelastic frequencies. Also, the hydroelastic frequencies increase as the fluid depth increases. More so, the increase in fluid depth tends to converge towards the uncoupled fluid free-surface frequency. The comparison of the analytical solution with experimental and numerical solutions does not match perfectly and thus, further works to improve this study are recommended.

The need for advanced ship propulsion control systems is constantly increasing as the demand for high vessel performance is growing at the same time. Speed trials are considered as an operation during which the vessel has to achieve the highest performance by attaining the agreed maximum ship speed. However, sometimes vessels have to sail in waves during speed trials. In such case, resistance and wake field disturbances act on the vessel’s propulsion plant causing fluctuations of the engine’s operating point in the engine operating envelope. When these fluctuations are large enough to reach the engine’s operating envelope limits, the propeller pitch control is activated to effectively protect the engine by reducing the propeller pitch. This decrease results in reduced average delivered power, reduced average generated thrust and finally in a drop of maximum average ship speed. This work focuses on investigating the possibilities to refine the existing control system by means of gain scheduling the Diesel engine speed governor. The ultimate goal is the re-sizing and re-orientating of the engine’s operating point fluctuations in the engine’s operating envelope, keeping the propeller pitch control deactivated and thus, the maximum average speed retained. First of all a linearised model of the ship propulsion system is derived which is used for the analysis of the Diesel engine’s operating point dynamic response in terms of engine torque and engine speed fluctuations in case of regular waves. More specifically, this thesis investigates the impact of the direction of the ship with respect to the waves, the Sea State and the system operating point on the dynamic response of the engine’s operating point in the engine’s operating envelope. Based on the analysis of the dynamic response of the engine’s operating point with respect to the three above mentioned factors and by making use of the linearised model, the refinement of the Diesel engine’s dynamic behavior is achieved. In the first place, a static solution is given with the derivation of suitable plots. The derived plots provide the opportunity for manual governor gains scheduling, depending on the wave induced disturbance. In the second place, a gains scheduling algorithm is obtained by combining the linearised ship propulsion model with an optimization algorithm. The developed algorithm, after being integrated in the non-linear simulation model of the ship propulsion system, is capable of dynamically scheduling the governor gains in case of regular and irregular waves. Both obtained solutions achieve the ultimate objective of this work. The fluctuations of the Diesel engine’s operating in the engine operating envelope are effectively re-sized and re-orientated. As a result the activation of the propeller pitch control is prevented and the average ship speed is retained.

Vessels are becoming more and more optimized towards their mission and an increasing amount of systems are considered during this optimization. Most of these considerations occur at an early design stage, where data is scarce and their impact is large. This research aims to aid designers in considering this growing forest of possible system using concept exploration. During this exploration both the mission of the vessel and the wishes of the owner of said vessel (or client) are considered. To do so a methodology is developed, which compares a large set of possible power plant configurations based on fuel consumption, emissions, system mass and volume. To obtain data for these four characteristics the design of each power plant is required. To obtain this the systems inside a power plant have to be designed individually. During the design of these systems several design choices are encountered. These choices are solved using the preferences of the client, which are defined as multi criteria weight factors related to the aforementioned characteristics. And as such create individual systems and from that a power plant configuration, which is optimal according to the client. The entire selection process is demonstrated using three separate cases; a bulk cargo carrier, a harbor tug and a Trailing Hopper Suction Dredger.

The time a naval combatant can be deployed for a mission is limited by its dependency on supplies. At a certain point the ship needs to leave the area of operations to be replenished in a harbour or by a support ship. Moreover, the Royal Netherlands Navy has a societal obligation to reduce its environmental impact, in particular on global warming. Therefore, the Royal Netherlands Navy (RNLN) wants to reduce the fossil fuel dependency of its fleet significantly [50]. One of the methods to reduce fossil fuel dependency of ships is to reduce their energy requirement. The operational profile of fast naval combatants for the RNLN requires that the ships operate on the diesel engines for 90 percent of the time, often in part load. In part load, the turbocharger cannot supply the engine with the right amount of charge air. This results in a limited operating envelope for the diesel engine, and a decreased efficiency in part load. This is caused by the matching of a turbocharger, which is a compromise between high efficiency in the design point, and off design performance. However, in part load, advanced charge air configurations can potentially resolve this and improve the results as shown by Grimmelius et al. [15] and Zhang et al. [56] This study investigates the effect of advanced charge air configurations on the efficiency and acceleration performance of diesel engines in hybrid configurations aboard fast naval combatants. First, two mean value first principle diesel engine models based on the work of Geertsma et al. [12] were used to model the diesel engine. Next, the models were partly validated with ship data. We found that an approach using compressor maps and a motion based turbocharger model was most accurate. Then, a parallel-sequential turbocharger and a hybrid electric turbocharger were incorporated into the model. A hybrid turbocharger is a turbocharger with an electric machine coupled to the turbocharger shaft. The electric machine can increase the turbocharger speed to boost the charge air pressure in motor mode. Also, in generator mode excessive power from the turbocharger shaft can be taken out and utilized elsewhere. It was concluded that the application of advanced charge air configurations can significantly improve the engine efficiency in part load. For example, in a diesel hybrid propulsion configuration with power take-off this can lead to an efficiency increase of almost 10% at 20% load in comparison with a single charged engine. Furthermore, hybrid turbocharging enables extending the operating envelope of a parallel-sequential turbocharged engine with up to 25% at 60% engine speed. This enables the engine to deliver constant torque from 600 to 1000 rpm. With these concepts therefore, both improved efficiency and improved acceleration performance can be achieved.

The shipping industry has a notable share in global greenhouse gas emissions and other pollutants such as sulphur and nitrogen oxides. Fuel cells and batteries are identified as relatively new technologies for shipping with high potential and hydrogen is also considered as one of the most promising sustainable fuels, especially for smaller vessels. This research contributes to three identified knowledge gaps: (1) the potential of hydrogen propulsion for high-speed craft, (2) the hybridisation of fuel cells and batteries for marine applications and (3) the characteristics of the response of a hybrid fuel cell/battery propulsion system under transient loads. The objective of this research is to analyse these aspects based on a series of time domain simulations of various operational conditions. A mathematical model of a fuel cell/battery propulsion system is developed in Matlab/Simulink. The developed model is used to analyse the energy consumption for various operational conditions of a test vessel. Based on this analysis, two configurations of fuel cell power and battery energy are selected. If the vessel sails at top speed, the fuel cell power stacks operate at maximum power and the battery operates as power booster. A strong correlation was found between the endurance at top speed and the battery size which is selected. A larger battery has a positive effect on endurance, but it also increases the displacement of the vessel significantly and, hence, required power. Fuel cells are least responsive and these should be protected against high fluctuations in a short time. A fuel cell can only follow low-frequency transient loads. The battery is required to support in high-frequency load changes. Contrary to the fuel cell, both the battery and PMSM were found to have very favourable characteristics in transient conditions. Finally, it is concluded that it is feasible to implement fuel cell/battery propulsion on high-speed craft. It is proposed that the fuel cell and hydrogen deliver the majority of the energy and use the battery as power booster and for transient support. Novel energy management strategies can deliver high system efficiencies in both full and part load and this is one of the main advantages of hybridisation. The implementation of a fuel cell/battery system does, however, come at significant costs in terms of endurance and top speed due to the low volumetric energy density of hydrogen. It should be acknowledged that the functionality of the vessel is reduced. In addition to this, the storage of hydrogen requires some deck space, so the cargo capacity in terms of crew and material is also reduced. Therefore, it is recommended to redefine the user profile of the vessel.

The maritime sector plays an important role in energy transition because offshore vessels are used for building offshore renewables but also have high emissions. The European Union (EU) has determined that from 2025 the maritime sector must pay per ton of CO2 emission. Heerema Marine Contractors (HMC) is an essential player in the maritime sector and plans to have reduced its emissions by 50% by 2025. This thesis aims to build a model in which different emission-abating options can be compared on financial and technical aspects to determine the best roadmap to achieve sustainability. To do this properly, literature research is done on emissions-abating fuels and technologies/processes applicable to offshore crane vessels. Five sub-questions are answered to find an answer to the main research question: What will be the future energy configuration of the Heerema fleet and the most technical and financial feasible roadmap to meet the sustainability goals look like? • What are an offshore crane vessel's main operational energy-consuming modes? • Which fuel switches and blends are technically and financially feasible, and what are the key characteristics of these fuels? • What are the key characteristics of the ship-based emission-abating technologies like batteries and carbon capture and storage? • What are the current vessel-specific levelized cost of Energy (LCOE) and levelized cost of carbon abatement (LCoCA) of the fuel switches and technologies, and how are they expected to develop over time? • Which emission-abating future scenarios are technically and financially feasible, and how will these sustainable roadmaps look? With the evaluation of the answers to these sub-questions, the importance of using hydrotreated vegetable oil (HVO) is shown until e-fuels are available. From 2026 e-fuels are assumed to be wide available for usage on board the three vessels, the Sleipnir, Aegir and Thialf the vessels within the scope. The financial evaluation of the e-fuels is in favour of ammonia. The technical evaluation is based on the limited available storage volume favour for methanol. These findings result in a roadmap using batteries on board the vessels together with HVO as fuel and when available installing designated ammonia or methanol tanks, and using ammonia or methanol as a 100% fuel blend in the internal combustion engines of the three vessels.

The ship propulsion system model is simulated by MATLAB/Simulink initially and is required to reproduce the simulation results in python. This master graduation project deals with the reproducibility of ship propulsion system model by different computer simulation tools. The MATLAB/Simulink model will be provided by Maritime Technology (MT) Department. The target is investigating and assessing the reproducibility of the ship propulsion model in python. During the pre-study, the stiff problem occurs due to many differential equations in the ship propulsion system. So, the initial python model could use the wrong method to solve the stiff problem and the initial python model cannot use variable time step to simulate the model. Even if the model cannot reproduce some experiments. The project should find a new reproducibility assessment method in python. The new reproducibility assessment method is first to analyze the model. This step can help us to know whether the simulation model is a stiff system or not. The report introduces a time-step test method for the stiff system with physical verification. At present, there is no exact definition of the stiff system. This method tries to find an effective way to test the stiff system. Next, introduce two Ordinary Differential Equation (ODE) solver methods. One is the explicit method; the other is the implicit method. Previously, published research has found that the implicit method can solve the stiff problem effectively. Therefore, the ODE solver is the key to the propulsion system model. Finally, the python modelling method needs to be improved, because the initial version model in python only uses fixed-time step. The new modelling method can apply a variable time step for the propulsion model. It will help to test the stiff system and save more computation resource. Once the new python model is finished, by comparing these two methods in MATLAB/Simulink and python, the plot presents the simulation result which is accurate and close to the reference result. The verification use Mean Squared Error (MSE) to indicate the reproducibility result. Each sample point of the two simulation tools is compared. The error plot will present what the difference between the python model with MATLAB/Simulink model. If the MSE value is close to zero, the reproducibility result will be successful. Finally, this graduation project gives the solution for the reproducibility assessment method in python. Study the stiff system solution for marine engineering, achieve the purpose of the reproducibility research and successfully reproduce the ship propulsion simulation model in python.