Nuclear power is currently not a commonly used option in commercial marine applications, despite its potential for significant emission reductions. This thesis is an overview of what has been done before, and what the potential is of modern marine nuclear power applications considering the long-term goals of harmful emission reduction in the maritime industry.
The concept of nuclear power is discussed, followed by the current state of nuclear power in both the shore-based, naval and the mostly historic marine application. The regulations for the marine application are noted to be outdated and require significant work for a successful application. Finally, the societal aspect of nuclear power is highlighted, as societal acceptance is not self-evident for nuclear power applications.
Different developments in the field of nuclear power are addressed, with specific interest in the SMR (Small Modular Reactor), concepts that are part of the “generation IV” family, and concepts that can operate using thorium as fuel. Multiple options are considered, from the well-established PWR (Pressurized Water Reactor) to the gen IV concepts: the HTR/VHTR (high/very high temperature reactor), fast reactors in both gas-cooled, liquid-metal and sodium cooled varieties (GFR, LFR, SFR) and finally the MSR (Molten Salt Reactor). Of these the HTR/VHTR and MSR in small modular reactor form are considered the most attractive option for the marine application, due to their passive safety, high burnup, high operating temperatures, and possibilities for thorium use in the future.
Criteria are established that are of importance to a marine propulsion and power generation system, establishing a framework for an implementation. Focusing on topics as: efficiency, transient loading capabilities, environmental impact, economic viability, size, and weight.
For power conversion (linking the heat generation to power/electricity for the vessel) the open-cycle Brayton turbine with a heat exchanger is selected as most suitable, despite the steam turbine being more developed and projecting a possible higher efficiency. The choice for the open-cycle Brayton turbine stems from the system size and weight reduction, along with a relatively easily implementable heat rejection system for enhanced load following capabilities. The selected heat exchanger is of the helical coil type, as this is significantly more developed and proven than the PCHE.
The most suitable layout is determined to be an all-electric layout, as this will greatly improve reliability (enhancing safety by redundant arrangements) and make the implementation easier applicable to a host of vessels. The electric layout allows for the combination of additional system such as batteries and emergency power. This layout is then combined with the open Brayton turbine and its heat rejection capabilities to ensure a system that is both compact as well as highly capable in performance.
Finally, four suitable concept vessels were established that allowed for a like-for-like replacement with a nuclear propulsion and power generation system. This allowed for a comparison to the conventional fuel-based systems where it is shown that the implementation of nuclear power can provide very large CO2eq reductions (over 98%), while reducing size and weight if vessels of suitable size are selected. The trade-off to this reduction is the production of nuclear waste, alongside the increased upfront cost due to the high capital investment associated with nuclear power.

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.

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.

The goal of this thesis is to characterise diesel-ammonia combustion using a mean value first principle approach, and to implement this characterisation of diesel-ammonia combustion in a time domain two-stroke engine model. This model will be used to indicate the technical feasibility of diesel-ammonia as a marine fuel. The main research question of this project is: How does the performance of the main engine of a deep-sea cargo vessel fuelled with diesel-ammonia compare to one fuelled by diesel only? The TU Delft engine B model is chosen to model the behaviour of an engine of an ocean going cargo vessel. The model has been adapted to simulate the behaviour of diesel-ammonia engines. The adapted model is used to compare the performance of a diesel only engine with a diesel-ammonia engine. The main conclusion from this study is that diesel-ammonia engine compared to diesel only engines have a higher specific fuel consumption because of the lower heating value of ammonia. Newly designed diesel-ammonia engines can potentially be more power dense because of stoichiometric air-fuel ratio of ammonia. However, the combustion efficiency could be a limiting factor. The diesel-ammonia engine emits significantly less CO2 and SOx emissions. However, ammonia emissions, caused by incomplete combustion, and an increase in NOx emissions, caused by the nitrogen in ammonia, are a concern. Furthermore, diesel-ammonia engines operate at lower maximum pressures and temperatures, therefore the mechanical limits of the engine are not exceeded. Lastly, diesel-ammonia engines do not require a different turbo charger system.

The use of fossil fuels and their impact on humans and nature is becoming a bigger concern worldwide. An interesting concept to lower polluting emissions coming from maritime engines is the combined use of a dual-fuel engine and an underwater exhaust system. In the dual-fuel engine natural gas is used as the main fuel type. It is seen as a cleaner alternative to the traditional fossil fuels that are being used. In order to ignite the air-gas mixture in the cylinder a small amount of diesel fuel (pilot fuel) is used, therefore making it a dual-fuel engine. Some advantages of using an underwater exhaust system are no direct emissions into the atmosphere, increased space on decks and reduced noise from the exhaust. However the downside is that such a system causes back-pressure effects which can deteriorate engine performance. So far research on these back-pressure effects on a dual-fuel type engine is lacking, therefore this thesis focuses on the static back-pressure effects on a dual-fuel engine.
For this purpose experiments were performed on a constant pressure turbocharged, 4-stroke dual-fuel engine. Engine performance and emissions were recorded for load points along the propeller and generator curve for three cases of back-pressure. The back-pressure was controlled by a butterfly valve in the exhaust pipe of the engine. Due to the fact that this butterfly valve could only be controlled manually, the back-pressure during the experiments could not be kept at a constant level. Also the engine experienced an absolute back-pressure of 1.15 bar with the valve fully open which was already quite high. And in the natural gas that was used a substantial amount of hydrogen was present. An existing diesel engine model (DE-B) that was developed at the TU Delft was then adapted to turn it into a dual-fuel engine model. It is a mean value first principle (MVFP) model. This dual-fuel MVFP model was then matched to the tested engine by using the experimental data. After the matching the model was used to test levels of back-pressure that could not be reached experimentally, due to engine limits, to see the effect on engine performance at these levels. The results were then analysed to see what the critical engine parameters are for the limits of the engine.
The experimental results showed that at low power more pilot fuel is needed to combust the gaseous fuel. It was also clear that there was a changing combustion efficiency for the gaseous fuel along the propeller curve. For the part load conditions the combustion efficiency was lower than at low or high power. For the generator curve the total efficiency was more constant, but always lower than the efficiency of the propeller curve. The results also showed that with increasing back-pressure the fuel consumption decreased for both the pilot and gaseous fuel, with the exception of the gaseous fuel flow at part load for the propeller curve. The recorded emissions showed lower levels of O2, CO and unburned hydrocarbons and higher levels of CO2 and NOx with increased back-pressure. Looking at the emissions in combination with the fuel flows, they showed signs of improved combustion efficiency with increased back-pressure. Increasing the back-pressure caused lower pressures and temperatures at the inlet side of the engine and higher pressures and temperatures at the outlet side. So for the thermal loading of the engine the outlet side is the critical one. The tested dual-fuel engine had a waste-gate installed. The model runs with higher levels of back-pressure showed that the pressure on the inlet side could become so low, that the pressure at which this waste-gate becomes active is no longer reached. This causes high pressures and temperatures before the turbine and high temperatures of the exhaust valve. The model also showed that at high levels of back-pressure the flow through the turbine becomes too low and not enough air is being put into the engine, so the air-excess ratio becomes too low, making the air-excess ratio also an important parameter for the engine limits. Finally it was shown how the dual-fuel MVFP model can be used to define acceptable limits of back-pressure for the air-excess ratio, exhaust valve and outlet receiver temperature.
The main recommendation for further research is to investigate the combustion efficiency of the gaseous fuel. Both the fact that at part load the efficiency was at it worst and the lower fuel consumption when back-pressure was increased need to be looked at. This will also help with improving the current dual-fuel MVFP model. Next to that it would be interesting to see what happens with different types of gaseous fuel and how the engine performs under a fluctuating back-pressure as induced by waves.

The constant pressure on the maritime sector to reduce Greenhouse Gas (GHG) emissions has led the shipping industry to search for alternatives, such as zero-emissions propulsion systems, which would allow meeting the 2050 target imposed by International Maritime Organization (IMO) regulation. Fuel cells have demonstrated to substantially contribute to the greening of energy conversion technologies. Specifically, Solid Oxide Fuel Cells have proven to be a reliable technology to produce energy from Liquid Natural Gas (LNG). However, the limited understanding of the effect of the components around the stack (also known as Balance of Plant, BoP) in SOFC power generation system represents one of the reasons of the slow development of this technology. The main objective of this research is to gain insight in the performance of the BoP components and their influence on the SOFC power generation system for maritime applications. A dynamic model describing a complete SOFC power generation system is developed in this work. The chosen system configuration consists of three blowers, two heat exchangers, a mixer, an external pre-reformer, an SOFC stack and an afterburner. Specifically, each BoP component is modelled dynamically using a 0-D approach and verified individually by using the software Cycle-Tempo. Then, the BoP models are integrated with an existing 1-D SOFC stack model. A dedicated control system is implemented and the load following capabilities of the complete system are studied. The model developed is able to simulate the time variation of all the BoP component characteristics and provides insights in the system efficiency when varying operating parameters such as stack current, anode recirculating ratio and fuel utilization. In particular, it is proven that working at low current enables higher cell voltage and, thus, higher system and stack efficiency. System fuel utilization significantly contributes to the system efficiency, which reaches the highest value for the highest fuel utilization. Additionally, the effect of the fuel utilization rate on the stack and system is the highest at lower currents. System and stack efficiency of respectively 58 % and 66 % are possible with the chosen system configuration. Anode recirculating contributes more to the system efficiency than the stack efficiency. The highest system efficiency is obtained for low current values and high recirculating ratio. Moreover, significant CO2 emission reduction is obtained for high recirculating ratio. The chosen control strategy succeeds on ensuring thermal safe operation, but does not guarantee fast response to load changes. In particular, a system response within 2 hours is achieved with the controller developed when the stack current is changed from 27 A to 23 A . Moreover, a load ramp of the stack current is a better choice in terms of thermal safe operation than a stepped change. The developed model represents a solid base for future development and research in the modelling of SOFC power generation systems for maritime applications. Nevertheless, future investigations on model validation, control system, start-up operations and system optimization are recommended.

The maritime sector faces major challenges with increasing regulations from the International Maritime Organization (IMO) and national regulations for CO2, SOx and NOx. Innovative fuel types for maritime use are now under development by various stakeholders. Methanol shows considerable potential as one of the most promising for implementation in the short to medium term, based on the potential availability, emission reduction, and energy density. The Green maritime methanol (GMM) project is Netherlands based collaboration of important stakeholders such as shipbuilders, engine manufacturers and universities. Within this project, methanol is researched as a potential alternative combustion fuel for maritime vessels. For this purpose, the ”Dutch Caterpillar engine dealer” PON Power provided a G3508A engine available as a retrofit option. The engine is a turbocharged spark-ignited natural gas (NG) engine with 8 cylinders and a rated power of 500 kWe at 1500 rpm. After six months of rebuilding the engine, the spark-ignited (SI), port fuel injected (PFI) engine runs on 100% methanol. Tests with stable engine operation were achieved with 100% methanol at 25%, 50%, and 75% engine loading and a constant engine speed of 1500 rpm.
In this research, experiments and modelling have been performed to study combustion using 100% PFI methanol. Measurements are realized with varying: ignition timings, NOx emission settings, and manifold temperatures. Data collected during these measurements such as in-cylinder pressures, emissions, and temperatures, provided a comparison between running the engine on methanol or natural gas. In this comparison combustion stability is determined with the coefficient of variation (COV) of Pmax and of imep, optimum ignition timing is determined and engine efficiency is calculated and compared to NG. Modelling is accomplished with a TU Delft model of the G3508A SI engine adjusted for the use of 100% methanol as a fuel. A modified sub-model for the PFI and vaporization of methanol has been developed. These engine data will be used to validate the methanol engine model and to optimise the engine performance for further experimental runs and better understanding the use of methanol as a fuel.
The effect on the performance and the combustion when 100% methanol is used as fuel for a SI PFI engine compared to premixed injection of natural gas is shown in this work. The engine operates stably on methanol at 50% and 75% load within ignition timings of 16-24 °CA BTDC, but less stable than with NG. Heat release indicates an almost similar combustion duration, but shorter combustion duration is shown for methanol. Also with methanol, the crank angle where 50% of fuel is burnt (CA50) is shown earlier compared to NG. The faster premixed combustion, combined with a better found fuel consumption operating point, resulted in higher efficiencies for methanol compared to NG for the tested 50% and 75% load at comparable operating conditions.

In the present study, a Model Predictive Control (MPC) - based, Energy Management Strategy (EMS) is proposed, aiming at the minimisation of the fuel consumption of vessels with hybrid propulsion and power supply. This approach is capable of utilising online information regarding realistic future predictions of the propulsive power demand, addressing the current gap in the literature regarding the implementation of MPC EMSs onboard ships, and pragmatic future mission information utilisation. To the author's best knowledge, MPC for fuel consumption minimisation has not yet been implemented at this timescale in maritime propulsion plants with hybrid power supply. Furthermore, online mission information from the Integrated Bridge Systems (IBSs) and the governor's human input cannot be utilised by EMSs onboard ships, due to the lack of a mathematical pathway to enable such an information feedback flow. Increasingly powerful processing units in ship controllers and a wider application of batteries in marine powertrains motivated such a computationally heavy and, simultaneously, highly fuel-efficient control approach. The proposed controller framework has been tested and verified in a case study using a Mean Value First Principle (MVFP) propulsion plant model of a hybrid naval vessel with batteries in Simulink®, provided by DAMEN® SNS. By using provided mission data, realistic mission profiles were generated, in which the proposed controller is validated against perfectly and piecewise, non-perfectly informed Dynamic Programming (DP) solutions in an information barrier scheme, yielding close to optimal performance, and a fuel consumption reduction of up to 3.5% when compared to any non-long-term feedback enabled controller.

Even though shipping is one of the mos fuel-efficient modes of transport, the industry was responsible for over 900 million tonnes of CO2 equivalent emissions in 2015. This is equivalent to the annual emissions of Germany. Besides greenhouse gas (GHG) emissions ships engines also cause particulate matter, NOx and noise pollution. As a result, the shipping industry is already facing strict rules and regulations, and these are expected to become even more strict in the near future. These developments have led to an increased interest in zero-emission solutions and one especially promising area is hydrogen-electric propulsion. By combining hydrogen produced from excess renewable energy with oxygen in a fuel cell, water and electricity are produced. The problem, however, is the storage method for hydrogen, traditionally hydrogen is stored in compression tanks under 300 to 700 bar. But due to the low density of hydrogen, this still results in large installations. Additionally dealing with large amounts of hydrogen gas requires extra safety precautions. An alternative way of storing hydrogen is by binding the gas to another substance like sodium borohydride or NaBH4. This substance is in a solid form and reacts with water to produce hydrogen and sodium metaborate (NaBO2). The NaBH4 crystals can be stored as a powder and are safe to handle under atmospheric conditions. Also, the substance has a high energy density, even comparable to that of conventional diesel fuel.

During offshore construction with a Semi-Submersible Crane Vessel (SSCV) the vessel is station keeping by means of Dynamic Positioning (DP). DP enables a vessel to keep position and heading by utilizing its own propulsion, while being exposed to the environmental forces caused by waves, wind and current. In a comparison study between offshore measurements and time-domain simulations, an increased vessel/thruster response for the offshore measurement was observed. The results revealed, that in operational environmental conditions, the measured vessel response shows increased oscillations in Surge, Sway & Yaw, with periods of approx. 3-5 min. The goal of this thesis was to determine the causes for such an increased dynamic vessel response, which are not captured in time-domain simulations. At present, numerical methods and time-domain simulations that assess the DP performance of a vessel (e.g. aNySIM) assume a quasi-static current of which the variation is only caused by the tides. One thesis is, that time-varying currents on a scale of 1 to 5 minutes can cause an increased vessel response. Furthermore, the DP System as it is used onboard is not captured in aNySIM simulations. This means that the characteristics of the DP System onboard are but not represented in full detail in time-domain simulations. Vortex Induced Motion (VIM) has previously been observed to affect multi column floaters. However, the influence on a SSCV during DP-operations has not yet been studied. In this thesis it was investigated whether the unexpected increased motions originate from time-varying currents, VIM or the DP System itself. A significant challenge was posed to find current measurement data with a small enough time step to confirm the presence of such time-varying currents. One 45 min current measurement with a sampling rate of 1Hz became available. This measurement shows that time-varying currents on a scale of 1 to 5 minutes exist and cannot be assumed to be quasi-static. More research is required to confirm their presence. However, with this limited available data it was shown that time-varying currents can cause an unexpected motion response of a SSCV during DP-operations.In order to obtain the DP System characteristics, a DP Response Amplitude Operator (RAO) assessment was conducted wherein the spring and damping terms were derived as demanded by the controller and as experienced by the vessel. This assessment showed that between 20% to 67% of the demanded critical damping is lost over the control loop of the DP System. These damping losses cause the vessel to overshoot and the damped natural period to decrease. To determine the effects of VIM, current load tests carried out on the hull of an SSCV have been investigated. It was determined that strong currents on column type floaters can cause fluctuating forces and moments that originate from vortex shedding. Further, with real-time simulations it was demonstrated, that also VIM causes an increased, previously unknown, motion response of a SSCV. Lastly, a method was developed to extrapolate the current load test results to velocities below 2kn. Subsequently, in time-domain simulations it was shown that for current velocities above 0.5kn, the vessel experienced forces and moments that caused it to fluctuate around its setpoint.

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.

Environmental regulations are continuously raising the bar towards more advanced diesel engine designs ca- pable of minimizing the emissions of polluting substances. The recent IMO Tier III legislation, entered into force in 2016, is forcing the engine manufacturers to meet a NOx reduction of more than 70% from Tier II for all the ships sailing in designated NOx Emission Control Areas (NECA). Although these zones are, up to now, limited to the North American and U.S. Caribbean Sea NECAs, future regions, such as the North Sea and Baltic NECA in 2021 as well as stricter national and port regulations, are increasing the uncertainty regarding the possible compliance methods.
The Selective Catalytic Reduction (SCR) represents a flexible, proven and commercially available technology capable of reducing more than 80% of the NOx in the exhaust gas. Its adoption started in the ’70s and was aimed at the reduction of stationary source emissions. From early 2000, it has been extended to the automotive industry in order to meet the Euro and EPA legislation for heavy duty and light diesel engines. Despite the evident disadvantages of the high installation cost and the considerable space requirements, the application of the SCR is subjected to a number of operating limits such as the narrow optimal temperature window and the slip of byproducts originated from the chemical reactions. These limitations can be even more severe when the diesel engine undergoes transient and dynamic operations.
The main objective of this research is to gain insights into the behaviour of the SCR technology under steady-state and dynamic operations of the diesel engine. After an accurate literature review of the working principles, reaction kinetics and modeling approach, a first principle model of the SCR has been developed to fulfill the scope. A 1D single channel approach, discretized along the reactor length, has been adopted to sim- ulate the heat exchange and the chemical reactions occurring in the catalyst. To facilitate the integration of the designed model with an existing diesel engine model available in the Maritime and Transport Technology Department of the 3me faculty, the resistance and volume approach has been selected. After the verification of the SCR model, the integrated system "SCR+Engine" has been tested under steady-state conditions, to an- alyze the effect that the added back pressure has on the engine performance, and under dynamic conditions, to simulate "real" load case scenarios that the SCR might experience.
The designed model, although limited from the chemical reaction point of view, is able to predict NOx reduction and ammonia slip under steady-state and transient operations. It can be further used in an early design phase to investigate the feasibility of the SCR inclusion in the drive trains of ships. Future studies are recommended to optimize the model, by taking into account the sulphur influence on the reduction efficiency and the catalyst aging, and to validate it with real experiments on marine SCR systems.

The rapid rate in technological advancements leaves little to none options for our environment to react. The excessive use of "conventional" energy is bringing planet Earth to its knees. However, people started recognizing the value of renewable energy sources.
One of the major renewable sources is the wind energy. The wind energy can be divided in two categories; onshore and offshore wind energy. Offshore wind energy has many advantages in comparison with onshore but comes with a major disadvantage, the installation cost. Since installing an offshore wind turbine is far more complex than installing the same wind turbine onshore, different ways needs to be developed to compensate for the excess costs.
Even though the cost is a significant aspect, it is not the most critical one. Since
more power is required, bigger offshore wind turbines are needed, thus larger foundation structures and bigger water depths. The conventional Jack-Up Barge that was being used for such operations so far is driving to a saturation on its operability due to limitations on maximum crane capacity and maximum water depth. For the aforementioned reasons, a floating vessel is considered to install bigger foundations but this leads to the loss of fixed ground that the Jack-Up Barge provided. This creates a significant problem that motions are generated and disturb the installation process. For this reason, a compensating strategy should be developed to allow such installations.
Such solution comes from TWD with the Motion Compensating Pile Gripper. In order to reduce the installation costs and to allow installation of wind turbines in higher depths of water, a floating vessel has to be deployed instead of the conventional Jack-Up Barges. The use of a floating vessel though, generates motions that disturb the installation procedure. This is the reason that TWD came up with a compensating gripper. This gripper uses hydraulic cylinders to generate forces for the monopile and vessel in order to counteract unwanted motions and to keep the monopile in the required position.
In this thesis, initially a functional design is conducted. This analysis concludes with the possible design strategies that can restrict the monopile through the lowering operation. After the possible design strategies are established, a simulation model is generated that involves environmental loads, a vessel model, a monopile model and a gripper model.
Through that simulation model, the different alternatives are tested and imulated
in order to evaluate the performance of each and observe their responses. Finally, after all the alternatives are simulated, a Multi-Criteria Analysis takes place that evaluates each one of the possible strategies based on various criteria in order to conclude to the winning strategy that is then suggested to be implemented in the lowering operation of the monopile erection process.

The diesel engine plays a dominant role in the field of (maritime) transportation and is expected to do so in the coming years. Depletion of fossil fuels and environmental impact are relevant concerns, widely acknowledged by the international community. NOx contributes to acid deposition and eutrophication. Regulations on NOx emissions become more stringent, such as the North Sea becoming a NECA area in 2021. In diesel engine emissions NOx mainly consists of NO.
Given the relevance of NO-emissions a prediction tool is useful. Hohlbaum has suggested a 2-zone in- cylinder model approach to predict NO-emissions. The cylinder volume is divided in two zones, one containing fresh air, the other hosting secondary combustion. In the flame front, which separates both zones, primary combustion takes place at an air excess ratio smaller than unity. Air also passes the flame front, effecting the composition in secondary combustion zone, where NO-formation is calculated using the extended Zel’dovich formulation.
The inclusion of gas properties by means of an equations of state is investigated as an opportunity to reduce the uncertainty in the assumptions in the original model formulation. Measurements on a 4 cylinder MAN engine are used to evaluate simulation results.
Matching the simulated cylinder volume to the actual cylinder volume using the fuel flow, requires an additional tuning parameter - the partition of the cylinder volume in two zones at start of combustion - since the original assumption no longer holds.
The original tuning parameter - the air excess ratio in the flame front - in combination with the newly introduced tuning parameter proved insufficient to match the simulated to the measured fuel flow. Therefore, the constant air flow passing the flame front is adjusted. Changing the flow profile made it possible to match the simulated to the measured fuel consumption. The simulated NO emission where 2.7 times higher than the measured values in the operating point investigated.
A more complete analysis of flow profiles at different operating points is still required.