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.

This master's thesis addresses the urgent need to reduce the marine industry's environmental impact. Van Oord, a marine player, aims to achieve carbon neutrality by 2050. The study investigates integrating methanol-fueled Solid Oxide Fuel Cells and batteries into the cable laying vessel NEXUS's power plant. The research shows that integrating these technologies can offer acceptable operational capabilities and substantial greenhouse gas emissions reductions in the medium term. However, short-term implementation faces challenges due to current SOFC limitations. Economically, long-term fuel cost savings make this integration viable, despite high initial capital expenditure. The study includes a literature review favoring SOFCs and methanol for cable laying vessels. The case study proposes a 1926 kW SOFC and a 1195 kW battery pack integration, resulting in significant fuel consumption and emissions reductions while complying with regulations. In conclusion, integrating methanol-fueled SOFCs and batteries in cable laying operations presents an opportunity for efficiency improvement and GHG reduction, with long-term economic benefits. This supports Van Oord's commitment to carbon neutrality and addresses the marine industry's environmental challenges

Cutter suction dredgers are a type of hydraulic dredgers often used in areas with hard soil where other types of dredging vessels would be ineffective. As a result of the wide range of type of soil that is being cut a lot of variation is seen in the power demand on the cutter suction dredger's diesel-electric power generation system. Consequently, the load on the main diesel engines rapidly changes. To smoothen power demand the addition of an energy storage system to the power generation system is investigated to reduce the load variation experienced by the main engines. Reduction of the load variation is also relevant for the application of dual fuel engines in cutter suction dredgers. For dual fuel engines exceeding of the loading limit poses a significant risk of the main engines switching from combustion of (liquefied) natural gas to combustion of diesel fuel to prevent misfiring or engine knocking. Better control of the engine load is expected to allow continuous combustion of liquefied natural gas during dredging operation. From the analysis of the power demand measured during dredging operation it is concluded that energy storage systems capable of delivering high power and have relatively low energy storage capability are best suited for this application. Based on the required characteristics flywheel energy storage and supercapacitor energy storage are selected as suitable energy storage systems. For both energy storage systems a simulation model is created based on available literature. A benchmark simulation model of the driveline of a cutter suction dredger, including the power generation system and electrical network, is created and validated using measurement data. The power and energy storage capacity of the energy storage system are determined by exceeding of the loading capacity of the main engines defined by the engine manufacturer during several months of continuous dredging operation. Separate cases are investigated where a supercapacitor energy storage system and a flywheel energy storage system are added. Simulation results are compared to the results of the benchmark model. Furthermore, simulations are conducted where the main diesel engines are replaced by dual fuel engines running on liquefied natural gas with a methane number of 80. Results show that both energy storage systems are capable of increasing the percentage of load variation within the engine limit on the original driveline from 91% to at least 99%. For dual fuel engines it is found that without an energy storage system 75% of the load variation is within the engine's loading limit, meaning switching to diesel fuel is inevitable during dredging operation. The addition of an energy storage system increases the percentage of load variation within the engine's loading limit to at least 98%. While the engine limit is still rarely exceeded, further analysis showed that the air excess ratio stays between the knock limit and misfire limit, meaning no switching to diesel fuel is required. As a result, continuous dredging operation using LNG as fuel is possible resulting in a reduction in fuel cost up to roughly 30%. During this research it is found that the effect of transient loads on engine wear could not be quantified. Further research into this subject is needed before conclusions can be made with regard to this subject. Also, no reduction in fuel consumption is seen as a result of the reduction of transient loading.

Maritime piracy has been a problem for the last decades and peaked in 2010. This resulted in large investments in anti-piracy measures, but as piracy waned over the following years, so did the investments in anti-piracy measures. This could be an indication that the stage for maritime piracy has been reset. This report suggests a more efficient and cheaper approach to counteract maritime piracy on merchant vessels indefinitely. SeaState5, the company at which this research is done, came up with the idea to combat pirate attacks on merchant vessels using a Fast Rescue Craft (FRC). Merchant vessels are obligated by law to carry an FRC; used for instance for man over board missions. SeaState5 focuses on developing an add-on plug and play system compatible with existing FRC. It turns these sole-purpose rescue craft into a multi-purpose craft, in this research referred to as the Beagle. This Beagle will serve both rescue and anti-piracy purposes. In this report the concept development of this add-on system is established. This is done by developing a simulation in MATLAB and Simulink that mimics a pirate attack on a merchant vessel. During the pirate attack the Beagle uses a defense strategy to repel the pirates. A Beagle defense strategy is a combination of a non-lethal weapon and a set of parameters that define the trajectory of the Beagle. Different Beagle defense strategies are subjected to different pirate attack scenarios to find the most effective one. The simulations resulted in a list of requirements for the Beagle. A check has been done to prove the feasibility of equipping an existing FRC with the add-on system meeting these requirements.

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 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.

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.

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 current global fleet is still dependent on conventional fuels as energy source to transport goods to various places in the world. These conventional fuels, such as MGO or HFO, emit large amounts of greenhouse gasses and other pollutant emissions. Regulation concerning these emissions becomes stricter every day, therefore institutions and governments have established reduction targets. To accomplish these reductions, net zero alternative fuels are serious candidates to investigate. As a result of these developments, Thecla Bodewes Shipyards is interested in solutions to reduce these emissions for their general cargo vessel series. Therefore, the objective of this research is to select the most suitable alternative fuel power- and energy system for a 7000 DWT general cargo vessel. In order to accomplish this objective, a literature review concerning potential alternative fuels is performed. After the selection of methanol as alternative fuel, the object of study is defined with specific boundaries and assumptions of the model. For the comparison of the current power- and energy system with future power- and energy systems, performance indicators are established and calculated. Subsequently, a case study is performed in which three concept designs for storage of methanol and two power plant configurations are proposed based on suitable energy converters on methanol and electrical load balance of the vessel. This research concludes that the fuel consumption of the vessel increased by a factor 2.1-2.4, range decreased by respectively 35% and 45% and payload decreased by 70 tonnes. Concerning the application of a methanol power- and energy system on board of a 7000 DWT general cargo vessel, a SI-ICE power plant with methanol as main fuel seemed most feasible.

This paper examines a case study to determine the effects on system performance of the power plant and ship operational capabilities, this case is a ship designed by the company DEKC. It is a small general cargo vessel of 2999 GrT (Gross Tonnage) called the Future Trader. The ship design is finished and the ship will be equipped with a modular power plant and fuel storage on the aft of the ship. In total four different power plants will be compared. The first is the base line system, this consists of a single internal combustion engine fuelled by Marine Diesel Oil (MDO). The three other systems will be modular systems. They all use the concept of distributed generation. There is looked into a system with three internal combustion engines fuelled by MDO. Besides this there are two fuel cell systems. Each consists of two separated fuel cells and one uses hydrogen and the second ammonia as fuel. For those systems mathematical models are created to compare three modular power plants to each other and to a base line. With those models the effects on the Future Trader's range, fuel costs (operational capabilities) and emissions are researched. A modular power plant is installed on the aft of the ship, constructed of four power packs each in a Twenty foot Equivalent Unit (TEU). The four systems will be simulated on four voyages and the results will be normalised with respect to the first setup. It can be concluded that a modular system with the concept of Distributed Generation (DG) will reduce the ships overall performance in comparison to the single engine diesel electric system (base line). When reviewing the fuel cell systems with respect to the base line system it is found that the ammonia fuel cell system has zero emissions and it still offers a sufficient range. The increases in fuel costs are lower than that of the hydrogen fuel cell system. Hydrogen will also reduce harmful emissions to zero but the reduction in range is more severe. The increase in fuel costs is also significantly higher than for the base line. Overall ammonia seems the most promising of the non hydrocarbon fuels. The DG system is also useful as long as emission regulations remain unchanged. The MDO DG system can be loaded for large distance voyages and hydrogen can be loaded for short voyages if desired.

Structures at sea, which can either be floating or bottom-founded, are always affected by several types of dynamic loads from wind, waves and currents; with floating offshore structures subjected to more motion and loading from these loads. Hence, necessitating more in-depth hydrodynamic analyses. Increasing size and weight of these floating structures together with industry demands have led to unsuitability of existing models – which make use of rigid body (no hydroelasticity) assumptions. This, in addition to other reservations about current practices, has led to the need for more realistic formulations of the interaction between fluids and our offshore structures, taking hydroelasticity into account. Extreme wave impacts, which are responsible for severe damage of offshore structures, have for a long period been only studied with experimental methods, as non-linear nature of the complex wave kinematics make solutions not straightforward. More recent advancements have seen the development of numerical techniques and programs, based on the Navier-Stokes equations, to better understand extreme waves and impacts on offshore structures. This thesis focuses on the topic of experimental validation of fluid-structure interaction (FSI) in ComMotion – an advancement in the ComFLOW program (an improved Volume of Fluid (iVOF) Computational Fluid Dynamics (CFD) code) to capture motion of flexible structures in the presence of free surface effects and a two-way coupling between the fluid and the structure. This has led to the need to provide reliable data for validation purposes. The research is conducted in continuation of the studies carried out by Rizos (2016) in which an electromagnetic drive linear motor produced noise and variable amplitude enforcement obtained in the analyzed results, amidst other uncertainties in the measurement techniques used. The current methodology principally makes use of a different motion technique – rotary to linear motion to obtain more reliable data. Firstly, rotary to linear motion was chosen (motivated from the internal combustion engine of an automobile) and then verified computationally with analytical derivations. The experiments were then designed, with the initial step being to verify the said linear motion. A sensitivity of the motion signal to weights in the system was carried out. Further, the experiment designed made use of a latex rubber membrane, applied with a clamped boundary condition at the bottom of a partially-filled rigid cylindrical structure. Tension existing in the membrane, due to water columns above it, was analytically obtained, as complete knowledge of system parameters was crucial. Linear oscillatory motion at the end of the converted rotary motion was applied to the fluid-structure system. Motion signals were obtained – rigid body measurements, to subtract them from the membrane motion measurements obtained. Motion measurements were acquired with laser triangulation displacement devices and a force transducer was used to monitor applied forces in the plunger during the experiments. The output of the transducer can offer validation data to the FSI solver. Membrane measurements were taken at half radius at a 30° step over a 180° span, and at the centre. This was in a bid to capture maximum deflections of the membrane, as interest was to obtain the coupled frequency mode shape. Finally, the obtained membrane motion data were analysed to prove their reliability, and to draw conclusions from them. Volume (of liquid), frequency and polar dependence analyses were carried out. Recommendations were subsequently outlined, for future research.

This study aims to provide a proof of concept of a plug-in hybrid electric superyacht. In this way, the yachting industry can help reduce carbon emissions worldwide and potentially increase comfort levels. The concept takes advantage of the typical operating profile of a yacht. A statistical analysis is performed to discretise this and obtain parameters for the all-electric design range at design speed. The available shore power is examined by means of a questionnaire. Three options to compensate the battery weight are presented to minimise impact on design. The resulting concept versions are checked for their potential impacts on four aspects: Design, Sustainability, Comfort and Operation. This includes a life-cycle assessment that results in serious impacts on sustainability at an all-electric range of 2% to 3% of the full range capability. Finally, the concept is tested by means of a test cruise.

The adverse human contribution to global climate change has forced the yachting industry to acknowledge the need to reduce its environmental impact due to the client's increasing pressure and potential future regulations to limit the ecological effects. Unfortunately, current real-world data presents a significant disparity between predicted and actual gathered energy consumption results. Thus, this research aims to develop an approach to accurately predict total dynamic Energy Consumption (EC) using real operation voyage data for the improved early-stage design of future yachts. A grey-box modelling (GBM) solution combines: physics-based white-box models (WBM); and black-box model (BBM) artificial neural networks to provide estimations with high accuracy and improved extrapolation capacity. The study utilizes ten months of onboard continuous monitoring data, hindcasted weather, and voyage information from a Feadship fleet yacht. Upon applying a sequential modelling methodology, predictions are compared between the three model categories, which ultimately indicated propulsion and auxiliary estimates fall within 3% and 7% error of operational conditions. The study is then continued using external range datasets to evaluate the extrapolation potential. While GBM improvements are seen over the BBM, limitations were directly related to the strength between dynamic WBM input-output correlations. Finally, a general consideration decision structure is detailed to provide naval architects with practical knowledge and confidence in future applications of the GBM modelling approach and when such methods are appropriate.

Traditionally, ships are powered by fossil fuels in combustion engines, causing 3% of global greenhouse gas emissions. Alternative installations have yet to prove their reliability and are currently not as cheap or technological ready. To enable ship-owners to prepare their ship for the future, but postpone their decision on which alternative installation to choose, it is the objective of this research to develop and validate a method for modular design of the power supply system of a ship, that allows a low-impact refit to lower the ship’s greenhouse gas emissions when the alternative power supply technology is ready. This method is developed within the scope of short-sea dry cargo vessels with little auxiliary power(<20%) that is to be refitted before 2050, but the method is kept as general as possible. The studied background information includes greenhouse gases, possible alternative installations, low-impact refits, and modularity. Furthermore, the method is verified and validated using two different case ships. In this report information about the method for modular design can be found, but also information on alternative power supply systems. The method is presented in chapter 5 and 6. It is concluded in chapter 7 that the developed method is effective and enables a low-impact refit, without significant negative impact on the initial design.It is concluded from this research that the method is effective and enables a low impact refit, without significant negative impact on the original design.For readers who want to know more about the alternative installations instead of the method, some basic information about available energy carriers and power supply units can be found in 2.3, the components of alternative installations of the case ship can be found in chapter 4 and the effect of those installations on the design to be found in section 5.3.

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.

Progressing targets on GHG emission reduction urge the the Netherlands Ministry of Defense (NL MoD) to reduce the use of fossil fuels, as they announced to contribute to the Paris agreement by reducing its dependency on fossil fuels by at least 70% by the year 2050. However, without sacrificing striking power, because future naval combatants need to perform their operations on the highest end of the violence spectrum and need to have sufficient autonomy to perform their operations at sea independent of logistic supply lines. The Royal Netherlands Navy (RNLN) is investigating the replacement of the Air Defense and Command Frigate (LCF) between 2030 and 2040 by a Large Surface Combatant. As it will be impossible to achieve substantial reduction of GHG emissions through energy-saving technologies, sustainable fuels need to be implemented in the design. In this thesis, the impact of sustainable fuel choice on the design of Large Surface Combatants with a displacement of around 6000 tonnes is assessed. In particular, the current and future developments of sustainable methanol and diesel have been reviewed from existing literature and are examined on the replacement Large Surface Combatant: specifically their advantages, disadvantages, production routes, future production cost estimates and availability to give an understanding which pathways can help the NL MoD to achieve their stated GHG emissions reduction goals. Furthermore, three different design concepts are presented with respect to fuel composition from which the impact of the established fuels is quantitatively examined. First, sustainable diesel is a drop-in fuel, which makes blending of sustainable diesel with fossil diesel possible in the existing infrastructure allowing a gradual transfer from fossil diesel to sustainable diesel. However, the production is less efficient in a well-to-wake approach and the cost of Bio-diesel and E-diesel is 5% to 30% more expensive with a mean estimated additional cost of 6 €/GJ compared to methanol. Secondly, operating on methanol has a significant impact on the design of a large surface combatant: the specific energy of methanol is more than twice as low as diesel and the ship needs a longer machinery space to allow for a diesel engine propulsion configuration. This results in a increase in displacement of 20%. Finally, navies could consider a two-fuel strategy: sail on methanol during operations with limited autonomy, typically in peace time, and operate on diesel during operations with high autonomy, during war time operations. In this case the design needs to include both diesel and methanol fuel systems and additional space for methanol safety measures. This results in a increase in displacement of 4%. However, the range when operating on methanol is reduced to 2187 nm compared to a 5000 nm baseline range. Assessing the impact of sustainable methanol and diesel for Large Surface Combatants at this level of detail and considering a two-fuel strategy is novel for the field. The results can be used by the Royal Netherlands Navy to compare the different concepts and serve as an indicative substantiation in the acquisition of a new Large Surface Combatant. Moreover, it can help in forming the strategy to migrate future naval combatants from current fossil fuels to future sustainable fuels.

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.

The formation of NOx in diesel engines is heavily influenced by the amount of available oxygen and the combustion temperature. This thesis investigates the effects of the implementation of exhaust gas recirculation on the NOx emissions of a 4-stroke marine diesel engine. With EGR implemented a part of the fresh intake air is replaced by exhaust gas. The exhaust gas contains less oxygen and has a slightly higher specific heat. This should result in a lower oxygen concentration and a lower combustion temperature. A mean value simulation model is used to simulate the engine and predictions of the NOx emissions will be made by using emission fits and certain engine parameters.

The design space of power plants of naval surface vessels is ever expanding. As a result, the design space has become too large for a human design team to fully explore. Therefore, a concept exploration tool is introduced to generate and evaluate all possible concepts within the design space. An optimal solution is chosen based on ship characteristics and client preferences. This tool helps designers find the optimal solution and visualises the design space to enable a less constrained design methodology.

With the increasing concerns of the emission of greenhouse gases and other pollutants and the push towards sustainable and greener means of transportation, there is a need for new drive systems running on alternative fuels. One fuel that holds significant potential as a marine fuel for the future is methanol. When produced utilising carbon capture methods and green energy, it has the potential to be a net zero fuel. Among other high-potential future fuels, methanol has the added benefit of being liquid at room temperature. Additionally, methanol has the potential to be utilised in novel drive systems, such as the combination of a solid oxide fuel cell (SOFC) and a reciprocating internal combustion engine (ICE). This concept utilises the high efficiency and negligible NOx formation of the SOFC, while the ICE provides dynamic load capabilities. This study concentrates on the electrical efficiency of this type of plant for maritime applications. This work presents an in MATLAB & Simulink constructed first principles based model of a methanol fuelled SOFC-ICE combined cycle. The zero-dimensional SOFC model consists of a temperature controlled methanator which maintains an external reforming ratio of 0.5; a cell mass balance; a cell energy balance, and an electrochemical model. The ICE model core consists of a turbocharged five-state Seiliger cycle. It simulates Wärtsilä 12V31DF fuelled with methanol and dehydrated hydrogen-rich anode of gas (AOG). The SOFC efficiency and its separate losses are evaluated for different temperatures, current densities, fuel utilisation factors UF and steam-to-fuel ratio’s in combined cycle operations. Additionally, the standalone SOFC performance, without the use of waste heat from the ICE and disuse of residual fuel in the AOG, is evaluated, but only for the nominal condition. The ICE efficiency and losses are evaluated for a power range between 1% and 100%. By varying the ammount of cells, the following power splits PSOFC/PICE have been evaluated: 0/100 25/75; 50/50; 75/25 and 100/0. The combined cycle performance is evaluated for different temperatures and current densities. This study found that while varying the steam-to-fuel ratio and fuel utilisation factor (UF) have minimal impact on the electrical efficiency of the SOFC in combined cycle operations, temperature and current density have a significant effect on the efficiency of the SOFC. For a steam-to-fuel ratio of 1:1, a UF of 0.8, a current density of 5000 A · m−2 and a mean cell temperature of 1073K an efficiency of 58.6% was obtained. The standalone SOFC, or 100/0 power split, obtained an efficiency of 48.4%. The stand-alone ICE genset, or 0/100 power split, operates at a nominal efficiency of 42.3%. When the ICE is used in a direct drive configuration, it corresponds to an efficiency of 43.6%. The combined cycle obtained efficiencies of 45.4%, 49.1% and 53.4% for 25/75, 50/50 and 75/25 power splits, respectively. These results are compared to the results of a similar study investigating an ammonia-fuelled SOFCICE combined cycle for maritime applications, which reported efficiencies of 47%, 50% and 52% for 25/75, 50/50 and 75/25 power splits, respectively, under similar operating conditions. The efficiency gain of the methanol-fuelled 75/25 configuration compared to the direct drive is limited. This raises the questions about whether the added complexity of introducing an SOFC is justified for the limited efficiency gain. The highest efficiency was obtained with the methanol-fuelled 75/25 power split, but due to the large proportion of SOFC power, it is less tolerant to dynamics in the load, making it questionable whether it can fully meet the dynamic power demand of a ship. Therefore, the 50/50 power split configuration is expected to be the most viable option in terms of both technological feasibility and efficiency gain. A change in the power split to 100/0 results in a decrease in system efficiency due to the lack of waste heat from the ICE and the inability to utilise residual fuel in the exhaust. When considering efficiency, the values for the ammonia fuelled and methanol fuelled plant are similar. The 50/50 powersplit configuration is 5.6 percentpoints more efficient than the methanol fuelled direct drive ICE and 1.2 percentpoints more efficient than the methanol-fuelled standalone SOFC. This clearly shows the synergistic benefits of combining a methanol-fuelled SOFC with an ICE. However, when compared to the ammonia fuelled combined cycle with 50/50 power split, it is 0.9 percentpoints less efficient. Nevertheless, it is important to exercise caution when drawing further conclusions from this last figure as the model has been constructed at a system level and no thorough uncertainty analysis has been conducted. Furthermore, the requirements regarding the power and energy density are strongly dependent on the type of ship and its operational profile. Therefore, future research should include the implementation of dynamic load capabilities in the model to evaluate its technological feasibility and overall net efficiency gain in various operational profiles of ships. Also, further research is required on the methanol-fuelled ICE cylinder process and the heat integration of the combined cycle.