The transition towards zero-emission inland shipping requires the integration of alternative energy carriers into hybrid propulsion systems. Sodium borohydride (NaBH₄), as a hydrogen carrier, offers potential as a range extender in hybrid battery-hydrogen vessels. Its application, however, is limited by high operating costs and limited data availability.

This study develops a high-level energy system simulation model to evaluate the operational performance of a small inland vessel powered by a hybrid battery and NaBH₄-based fuel cell system. The model, implemented in MATLAB/Simulink, represents energy flows from vessel operation to propulsion and hotel loads, and includes a simplified stoichiometric reactor model combined with a discrete control strategy.

The model is applied to the Neo Orbis, an emission-free vessel operated by the Port of Amsterdam. Results show that system performance is strongly influenced by the interaction between battery utilisation, fuel cell operation, and control logic. In particular, fuel cell activation timing and state-of-charge control thresholds significantly affect fuel consumption, battery usage, operational flexibility, and operating costs.

The findings demonstrate that system-level insights can be obtained despite limited component data, providing a flexible framework for the design and optimisation of hybrid maritime energy systems. ... Read more

Modern DC power systems consist of a large number of power electronic converters and associated
equipment. On a ship, this power system is typically divided into two identical parts on the port and
starboard sides. These duplicated power systems are often isolated from each other to prevent a fault on one side from propagating to the other side and affecting the entire system, avoiding a total blackout on the ship. A major drawback of this two-split configuration, though, is that it is impossible to share power between both sides, reducing the functionality of the system. Therefore, to connect both sides while maintaining the safety of an isolated system, a solid-state circuit breaker (SSCB) can be used, which is reusable, unlike a fuse, and is able to interrupt the current much faster than a standard mechanical circuit breaker. However, due to the relative novelty of this component, the impact of mission profile variation and electrical disturbance on the SSCB lifetime is unknown.

To obtain the SSCB lifetime, mission profile analysis was performed, resulting in a lifetime as a consequence of wear-out failure mechanisms due to thermomechanical fatigue that would be used as the base case. Based on the mission profile, an SSCB model was designed following considerations for: Current interrupter topology, rated voltage/current of the components, peak voltage/current of the components, voltage clamping circuit, and the cooling. After choosing suitable components, their junction temperature profiles were obtained via iterative calculations with the power loss and the junction temperature using a Cauer model without thermal capacitance. With the rainflow counting algorithm, information regarding the cycle count, temperature swing, mean temperature, minimum temperature and the power-on-time per class was obtained. These were used in the CIPS with correction lifetime model, which obtained the cycle-to-failure of each relevant component. Transforming them into a reliability curve per component and multiplying them together resulted in the reliability curve of the SSCB. To estimate the impact on the lifetime of the electrical noise through the SSCB in comparison to the mission profile, a dynamic model was designed to take thermal capacitance into account, unlike the iterative model.

To quantify the impact of different stressors on the SSCB lifetime, changes in the mission profile, SSCB configuration and operational parameters compared to the base case are made. It was seen that the charging current, corresponding to changes in the maximum stress within the mission profile, has the most significant impact on the SSCB lifetime, while having a relatively minor drawback of a varying charging period. Bi-directional charging and changes in the coolant temperature were shown to have a relatively low impact on the lifetime. Load sharing between parallel components in a module significantly increased the lifetime, but at a cost of practically investing in a second SSCB. Concerning the impact of noise on SSCB lifetime with respect to the damage done by the mission profile, it can be concluded that high-frequency noise, such as the common-mode and differential-mode noise, has a negligible effect on the lifetime of the SSCB when solely focusing on wear-out mechanisms due to thermomechanical fatigue. ... Read more

This thesis explores the potential of Variable Speed Generators (VSGs) within hybrid DC power systems for next-generation Anti-Submarine Warfare (ASW) frigates. As naval operations increasingly prioritise efficiency, emissions reduction, and adaptability to transient load variations, VSGs present a compelling alternative to conventional fixed-speed AC generators. While VSGs offer notable improvements in fuel efficiency, their transient performance under dynamic operating conditions remains a critical area of investigation. To assess these dynamics, a mean value simulation model was used and validated against Factory Acceptance Test (FAT) data and naval standards. The findings reveal a fundamental trade-off: although VSGs enhance fuel efficiency in steady-state operations, their transient response presents challenges, particularly in thermal management and stability. Slow turbocharger dynamics lead to prolonged inadequate air excess ratios during load transitions, resulting in incomplete combustion, excessive soot formation, and increased thermal stress. Additionally, VSGs exhibit difficulties in managing speed and voltage fluctuations during abrupt load changes. Despite these challenges, the study identifies several potential solutions, including electrically assisted turbochargers, advanced energy storage systems, and hybrid control strategies. These innovations can mitigate transient inefficiencies, enhancing both stability and responsiveness. In conclusion, while VSGs represent a significant advancement in naval power systems by combining fuel efficiency with operational flexibility, their successful integration requires targeted improvements in dynamic performance and system-level optimization. By addressing these limitations, VSGs can evolve into a more resilient and robust power solution for next-generation naval vessels. ... Read more

The transition to more sustainable operations is being widely adapted in order to reduce the green house gas emissions and meet future sustainability requirements. This transition most often utilizes electrification as a means to reduce emissions and utilize renewable energy sources. This transition comes with extra burden on container terminal authorities who have to manage their power demands and transmission and distribution system operators who have to keep up with providing this growing electricity demand.

This comes with extra costs as distribution system operators have to build and maintain a larger network and larger power capacities can not always be ensured for consumers such as container terminal authorities due to grid congestion. To achieve electrification for container terminals these distribution system operator costs as well as electricity costs and a congesting grid should be taken into account. To combat this, this thesis will analyze the electrification for a container terminal with a case study considering these factors.

However, scheduling power demands for container terminals is not trivial as they operate in a very dynamic and uncertain environment. This stochasticity is caused by uncertainty due to for example uncertain energy generation or uncertainty in operations, such as arrival time of ships. To ensure a container terminal has sufficient electric capacity and can manage its power demand for the day-ahead around this uncertain arrival time, a two-stage stochastic power optimization is modeled.

This optimization takes into account the flexible resources which a container terminal could benefit from, such as a battery energy storage system and flexible cooling of refrigerated containers. The charging decisions for the electric yard fleet as well as charging and discharging of battery energy storage system and cooling of reefers are scheduled for the next day. Power such as shore power and crane power for berthed ships which are loading or unloading are considered uncertain due to the uncertainty in arrival
and its deviation from the estimated time of arrival will be taken into account.

In this two-stage optimization where the aforementioned uncertain loads are second stage decisions, while decision such as when to charge batteries or cool refrigerated containers are made beforehand and therefore belonging to the first stage decisions. This stochastic two-stage optimization with uncertain ship arrival time is then solved with the progressive hedging algorithm, which decomposes the possible ship arrival scenarios in to individual solvable problems. These solutions are then pushed towards a common decision value through a penalty term.

With this model it is found that with the current electric contracted capacity, full electrification of the port equipment will not be a viable option. The necessary capacity is then optimized considering the flexible resources and electricity pricing. Dynamic electricity pricing will utilize a higher capacity to benefit from the lower electricity prices by charging and cooling at these times, despite the cost for a higher capacity. Despite these higher distribution costs, the total costs for electricity for a dynamic electricity price contract is significantly lower, minimally 23.65 % lower for the same configuration. A Time Constraint Transport Right is also analyzed, which could work for container terminals with many flexible loads, but this does not provide more incentive compared to a regular contracted capacity. ... Read more

This thesis explores the potential for enhancing the operational efficiency of deep-sea mining through the semi-real-time modelling of the Vertical Transport System (VTS) and umbilical positioning. As the demand for rare earth minerals rises with the global shift toward renewable energy, deep-sea mining has emerged as a crucial method for resource extraction. However, the complex and dynamic nature of deep-sea environments presents significant challenges, particularly in ensuring the safety and efficiency of the mining equipment.

The thesis develops a computational model that simulates the position and dynamics of the VTS and umbilical in semi-real-time, providing predictive insights for operational decision-making. The model incorporates a shape calculator for the umbilical, jumper, and riser, a current finder to estimate ocean currents, collision detection, and a P-turn optimisation algorithm to improve manoeuvring efficiency during mining operations. By integrating sensor data and environmental conditions, the model offers real-time feedback and predictive analysis, aiding operators in minimising risks such as ground collisions and equipment entanglement.

The model’s accuracy was verified against OrcaFlex, a widely used marine simulation software, and data collected during a pilot mining test (PMT). The verification process demonstrated that the model’s predictions are within an acceptable error margin of less than 1% of the total length of the umbilical, confirming its reliability for practical application. Additionally, the model's P-turn optimisation showed the potential to reduce the distance travelled by the vessel during turns by up to 35%, translating into significant time and fuel savings for mining operations.

While the model offers valuable insights and improvements in operational efficiency, the research also acknowledges its limitations, including the simplification of certain environmental factors and the need for more detailed modelling of the riser. Future work is recommended to expand the model's capabilities, particularly in incorporating three-dimensional movement, enhancing fuel efficiency considerations, and further refining the optimisation process for P-turns.

Overall, this thesis demonstrates that semi-real-time modelling of the VTS and umbilical is a viable method for improving the efficiency and safety of deep-sea mining operations, contributing to the sustainable extraction of critical resources. ... Read more

To more effectively reduce carbon emissions from ships during op- eration, utilizing hydrogen as a fuel for ship engines has emerged as a promising direction. Given the unique physical properties of hydrogen, targeted modifications to existing engines are necessary for adaptation. In hydrogen-fueled engines, the injection system is a critical component. This study aims to adjust the design parameters of a novel injector to match large two-stroke ship engines and to theoretically demonstrate the feasibility of this novel injector for use in large two-stroke engines fueled by hydrogen.Currently, the ma- jority of hydrogen-fueled engines are four-stroke engines, typically employing high-pressure injection. However, high-pressure injection tends to shorten the lifespan of the injection system, consequently reducing the overall lifespan of the engine. Therefore, this study proposes a low-pressure injection scheme, combined with in-cylinder direct injection, to mitigate the risk of unintended ignition. Given the high autoignition temperature of hydrogen, spark ignition is employed to facilitate ignition. A critical step in evaluating feasibility is determining the appropriate injection timing.Initially, it was es- tablished that hydrogen should be injected after the commencement of the compression stroke to achieve optimal mixing. Subsequently, the study analyzed the in-cylinder pressure variations during the compression stroke to identify the feasible injection window. Finally, the design parameters of the injector were configured to align with these conditions. The findings theoretically demonstrate that this injector can achieve low-pressure direct injection in large two-stroke hydrogen engines.Due to time constraints, the study did not inves- tigate the effects of different injection angles and positions on the engine. Nonetheless, the theoretical analysis confirms the feasibil- ity of employing low-pressure direct injection in large two-stroke hydrogen engines. ... Read more

As climate change concerns increase, the maritime industry faces an urgent need to reduce emissions and adopt sustainable practices. The integration of hybrid systems, particularly those incorporating Battery Energy Storage Systems (BESS), has emerged as a promising solution to enhance energy effi- ciency and lower the environmental impact. This Master Thesis focuses on developing a methodology for determining the most suitable battery size and type for existing vessels to be hybridized, balancing effectiveness and cost-efficiency. This thesis was conducted in collaboration with Jan De Nul Group, a leading global firm in environmental services, engineering, marine construction, and dredging.

The primary goal of this research is to design a methodology that compares different control strate- gies for sizing battery systems and selecting appropriate chemistries. A case study based on a trailing suction hopper dredger vessel was explored.

Three control strategies were evaluated using numerical modeling: optimal operation of the current scenario without batteries, load smoothing using a moving average approach, and optimal range op- eration of generators. To optimise the number of running generators and reduce maintenance costs, an automatic start-stop logic is implemented as a model initialisation. The optimal operation of the current scenario without batteries highlights the need for battery integration to compensate for the high supply deficit. In addition, the load smoothing strategy creates a more stable demand curve, allowing generators to operate more efficiently, while the optimal range strategy keeps generators near their rated power, maximizing efficiency and minimizing fuel consumption.

The study assesses battery performance under two scenarios: continuous full cycling throughout the year and calendar aging specifically during harbour operations. Battery power is calculated based on demand and generator output, considering state-of-charge constraints. Three types of lithium-ion batteries were evaluated for their suitability in ocean-going hybrid vessels: Lithium Nickel Cobalt Manganese Oxide (NMC), Lithium Iron Phosphate (LFP), and Lithium Titanate Oxide (LTO).

A total of 648 battery solutions under the load smoothing strategy and 216 under the optimal range strategy were assessed. Using four key criteria, the selection of battery options was narrowed down. Given the limitations of the model used in this research, findings suggest that batteries affected primar- ily by calendar aging have shorter lifespans, making cycling behavior preferable for achieving longer battery lifetime and higher Return On Investment (ROI). The optimal range strategy leads to higher fuel savings compared to load smoothing, while load smoothing results in a longer battery lifespan due to fewer equivalent cycles. In summary, selecting the best battery solution hinges on whether the priority is immediate ROI or long-term operational efficiency. This thesis offers a comprehensive methodology for integrating BESS, contributing valuable insights to the advancement of sustainable energy solutions in the maritime sector. ... Read more

One fifth of the global carbon dioxide (CO2) emissions can be attributed to the transportation sector. Consequently, the growing desire to participate in the energy transition begs for the exploration of alternative modes of transportation. This endeavor is particularly challenging in the field of aviation and aircraft propulsion, where the injection of electrification and electric motors (EMs) pose many hardships such as the need for high autonomy, light weight, high power density and reliability. This work will mainly focus on the latter.

Unlike the low voltage machines used in road mobility, the motors necessary to propel an airplane demand substantially higher voltages due to their power requirements. Despite the availability of dielectric materials and insulation techniques, an improper design of the insulation system may make it susceptible to electrical stress, possibly reaching its breakdown voltage, generating partial discharges (PDs) and degrading the insulating material overtime. This will eventually lead to the electrical failure of the machine.

This danger is further increased by the recent rise in popularity of new wide-band gap power electronic devices. These devices offer many advantages: reduced size and weight, the ability to operate in higher temperatures, and the improved efficiency due to the reduction in power losses, caused by their steep switching speed in the order of 10−100 ns. However, the steep voltage transients (dv/dt) they produce create harmful side-effects to the machine. Firstly, the feeder cable connecting the voltage inverter to the machine terminals suffers Reflected Wave Phenomenon (RWP), where the voltage pulses are reflected at both ends of the line generating intereferences, which in turn generate overvoltages that can rise to up to twice the original voltage pulse. Secondly, the inherent leakage capacitance between the cable turns and the core of the stator slots produce an uneven voltage distribution along the wiring turns. These effects could increase the voltage stress in the insulator and momentarily reach the breakdown voltage in certain points of the geometry, producing Partial Discharges (PDs) that degrade the insulation over time.

To avoid this degradation, the aim of this thesis is to study these harmful effects in depth, back-up the literature review with accurate simulations and experimentation and realize the worst case scenario considering the geometry of a given motor that is currently under design. Once the phenomena is understood, some mitigation techniques are proposed to lower the chance of any discharge occurring. ... Read more

Carbon corrosion occurring on the cathode of a polymer electrolyte membrane fuel cell (PEMFC) leads to a reduction in the electrochemical surface area (ECSA). The ECSA is crucial for the efficiency and maximum power output of the fuel cell. Degradation of this component is detrimental to the overall performance of the system. Research into the mechanisms of ECSA degradation is essential for understanding and preventing fuel cell deterioration. The carbon in the electrode functions as a support material for the catalyst and provides the necessary electrical conductivity. Carbon corrosion can increase resistance between the electrode and the catalyst, and research suggests it may even cause the catalyst to detach from the electrode. This thesis investigates carbon dioxide emissions from a PEMFC during an accelerated stress test (AST), measured using a gas analyzer. The exhaust gases contain
approximately 600 parts per million (ppm) of carbon dioxide, fluctuating by about 100 ppm throughout the day. A fluctuation of 80 ppm, attributed to changes in oxygen content during the operational and shutdown phases of the PEMFC stress cycle, was also identified. A formula was applied to remove these fluctuations to better understand the emissions. Carbon dioxide emissions were detected during the startup phase, when a hydrogen-air front is active at the anode, making carbon corrosion at the cathode likely. The area under the emission peak was determined and multiplied by the flow rate, providing an estimate of the carbon dioxide emissions and the corresponding carbon mass loss from the cathode. A secondary objective of this thesis was to validate a mathematical model of carbon corrosion with the obtained data. However, this was not possible with the current data set. The model does
not account for the dynamic conditions of the stress test, which are typically significant contributors to carbon corrosion in a PEMFC.
... Read more

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

The Global Shipping industry is responsible for transporting 90% of global commerce and is responsible for 3% of global greenhouse gas (GHG) emissions. Addressing this, the International Maritime Organization (IMO) aims to reduce GHG emissions from international shipping by 40% by 2030 and achieve net zero by 2050. This study explores Low Temperature-Proton Exchange Membrane Fuel Cell (LT-PEMFC) hybrid energy systems as a potential solution to reduce shipping emissions. Emphasizing the operational zero-emission capability of PEMFC fueled by hydrogen, the research scrutinizes the emission intensity from hydrogen production and the impact of component degradation on hybrid system efficiency and hydrogen consumption.

The research pivots around optimizing the design and operation of ship hybrid energy systems to minimize costs while considering well-to-wake (WTW) emissions and component lifetime. It investigates two hybrid configurations: PEMFC/Li-ion battery (LIB) and Diesel Generator (DG)/PEMFC/LIB. Employing a Mixed Integer Linear Programming approach for component modeling, the study conducts a two-stage analysis: design optimization considering various hydrogen sources and plant lifetime estimation focusing on PEMFC and battery degradation.

Initial findings reveal that system design costs do not significantly differ across hydrogen grades. The DG/PEMFC/LIB configuration emerges as cost-effective, reducing CAPEX by 62.8% compared to the PEMFC/LIB setup. Carbon Capture and Storage (CCS) hydrogen grades strike a balance between cost and emission reduction, notably cutting emissions by up to 85% in the PEMFC/LIB configuration at a 27% OPEX increase.

Lifetime estimation highlights the effectiveness of a hierarchical optimization method in mitigating PEMFC voltage loss and extending component lifespan, albeit with increased battery cycling aging. The study underscores the importance of selecting the appropriate hydrogen grade and operational strategies to enhance the sustainability and economic viability of maritime hybrid energy systems, aligning with IMO’s emission reduction goals. ... Read more

There is currently a resurgence of interest in nuclear propulsion within the maritime sector, which is reflected by the ambition, as mentioned in the Dutch maritime sector report "No Guts, No Hollands Glorie", to develop a standardized, modular nuclear reactor for ship integration within 10 years. Nuclear energy has the potential to reduce the maritime sector’s contribution to climate change, as it does not emit CO2 during operation. Additionally, in contrary to many other renewable energy sources, nuclear energy offers a high-energy-density power source capable of providing sufficient energy for longer periods of operation. Not only would this improve the strategic autonomy of the Royal Netherlands Navy, but it would also be a solution for the increasing energy demands of additional unmanned systems or advanced combat systems, like high power radars and rail guns.

Implementing nuclear propulsion in future (naval) vessels presents challenges, particularly regarding the dynamic power profile of ships during operation. Land-based nuclear reactors typically operate as stable power sources, which contrasts with the fluctuating power demands of ships, especially naval vessels. This research aims to find a solution for these dynamic power requirements, without the use of energy storage capabilities, like batteries, for peak shaving capabilities.

Based on the expected implementation of a small modular reactor (SMR) by 2034, the Future Air Defender and the Amphibious Transport Ship were selected as potential vessel types of interest for the Royal Netherlands Navy to implement an SMR. Additionally, the high-temperature gas-cooled reactor (HTGR) and the supercritical carbon dioxide (sCO2) recompression power conversion cycle were selected for the nuclear power plant. A dynamic model of the selected SMR and its energy conversion system has been developed to compare its ramp rate with those of conventional naval prime movers, such as diesel engines and gas turbines.

The simulation results indicate that the reactor dynamics alone are insufficient to meet common ramp rates of naval vessels, demonstrating that relying solely on reactor control is not a viable control strategy. However, the implementation of the turbine bypass valve, while operating the reactor at a constant load, provides dynamic power behaviour comparable with diesel engines and even gas turbines. Potential drawbacks include reduced cycle efficiency at part load, as well as significant pressure and temperature gradients within the heat exchangers. The unacceptable temperature increase at the reactor’s inlet was addressed by incorporating a dump cooler into the primary circuit. This research therefore concludes that an HTGR, in combination with an sCO2 cycle and a bypass valve, is capable to provide the dynamic power requirements of a naval vessel.
... Read more

Rotor imbalances—such as mass imbalance, pitch misalignment, and yaw misalignment—are critical faults in wind turbine systems. These imbalances cause uneven load distribution on components, leading to excessive wear, failures, increased operational costs due to unplanned downtime, and reduced energy output. Despite advancements in monitoring technologies, current maintenance strategies in wind turbines still rely on time-based manual inspections, as they lack reliable automated detection systems. This thesis addresses the need for a more efficient fault detection framework by integrating already available drivetrain Condition Monitoring System (CMS) vibration signals— commonly used to detect drivetrain component failures, like in gears and bearings— with traditional SCADA data. The aim is to extract signal features that capture the system's dynamic behavior and effectively detect and diagnose rotor imbalances. Notably, this approach overcomes the limitation of current systems not having direct measurements from the blades by leveraging operational data already collected from wind turbines.

Building on prior research, the proposed approach combines frequency and time-domain analyses and focuses on two key data sources: drivetrain vibration measurements and rotor speed data from the SCADA system. A decoupled simulation framework integrates aeroelastic simulations from OpenFAST with a multi-body drivetrain model in SIMPACK, specifically for the 10 MW DTU reference wind turbine. The results show that drivetrain velocity signals, particularly in the side-to-side direction, are highly sensitive to rotor imbalances, enabling accurate trend analysis. Features such as peak amplitudes at 1P and 3P frequencies form the basis of the fault detection and diagnosis criteria proposed in this thesis. By using the median values of their distributions, imbalances can be effectively detected and diagnosed. This approach also supports the implementation of a decision tree framework for real-time fault classification across various operating conditions.

The methodology was tested under both above and below-rated wind speeds, first in steady-state conditions and then in turbulent inflow scenarios. Additionally, health state indicators are proposed to recognize fault severity levels by clustering median value features within predefined ranges for low, medium, and high severity. This comprehensive monitoring approach effectively tracks fault progression across the imbalance scenarios under study. As a result, the proposed method lays the foundation for a future data-driven system that can reduce reliance on manual inspections and provide a scalable solution for predictive maintenance in wind turbine operations. ... Read more

A new simulation tool has been developed to provide insights into the refueling process of hydrogen. The tool is based on existing models, including a 0D gas model and a 1D wall model, which have been refined to assist companies like Future Proof Shipping, which rely on compressed hydrogen tanks. Although the model is still subject to changes and not fully reproducible during the validation process, it has accurately computed the temperature evolution for large tanks ranging from 1500-2100L. Based on this evolution, it is recommended to maintain the inlet temperature of hydrogen at -20°C or lower. Furthermore, it is suggested that Future Proof Shipping should consider using a type 3 hydrogen tank, which features an aluminum liner and better heat conductivity. This results in more efficient heat conduction away from the hydrogen. ... Read more

Currently, our society faces a pressing challenge: global warming. The solution lies in the energy transition, which replaces fossil fuels with clean sources. This requires a global effort across all sectors, including shipping. While a significant portion of shipping relies on polluting fuels, the European Union’s Green Deal aims for climate neutrality by 2050, which applies to shipping as well. Emission reduction technology and low-to-zero emission energy supplies are emerging, yet choosing the right energy supply for new vessels remains complex, especially in meeting EU targets.
This study focuses on supporting the decision-making process for the energy supply of a new Semi-Submersible Crane Vessel (SSCV). The method facilitates a comprehensive comparison of energy supply options using multiple criteria. It also integrates decision-makers’ preferences with the characteristics of alternative energy supplies, providing insights into the most suitable choice. This research features a case study centered on Heerema Marine Contractors’ SSCV Sleipnir.
To create this method, a literature review on Multi-Criteria Decision Making (MCDM) methods was conducted. The Analytic Hierarchy Process (AHP) model was chosen as the foundational framework for the decision-making tool. During the research key limitations and requirements for designing an energy supply for a SSCV were identified. Furthermore, the research contains an examination of various fossil and sustainable fuels, including Marine Gas Oil (MGO), (E-)Liquefied Natural Gas ((E-)LNG), EHydrogen, E-Methanol, E-Ammonia, Uranium, and Thorium. Additionally, the study considers diverse energy conversion systems including Internal Combustion Engines (ICE), Proton Exchange Membrane Fuel Cells (PEMFC), Solid Oxide Fuel Cells (SOFC), Direct Methanol Fuel Cells (DMFC), Molten Salt Reactors (MSR), and Very High-Temperature Reactors (VHTR). A set of significant criteria are identified and the accompanying characteristics of the energy supplies regarding these criteria are gathered. The literature research is followed by a financial assessment. This assessment shows that the financial impact of fossil- and e-fuel energy supplies is highly dominated by Operational Expenditure (OPEX), while the nuclear energy supplies are highly dominated by its Capital Expenditures (CAPEX).
The preferences of Heerema’s decision-makers are collected via a survey, revealing that the Technological Readiness Level (TRL) of the system, health risk, emissions, Levelized Cost Of Energy (LCOE), maintenance requirements, and efficiency of the conversion system are found to be the most important criteria according to the survey results. The preference weights assigned to the criteria are integrated with the energy supply characteristics, providing a score that indicates the suitability of each energy supply considering the SSCV’s limits and requirements, aligned with the preferences of the decision-maker. Hence, the optimal energy supply choice can be deduced from this data.
Although the fossil fuel MGO is included to act as a base-case scenario during this case study, the results of the method show that MGO used in an ICE would be the best-suiting energy supply according to the preferences of the decision-makers. Since MGO energy supplies are assumed to be non-compliant with the EU-emission goals they are excluded. When excluding MGO from the results, methanol used in an ICE is identified as the best-suiting alternative. This can be attributed to its relatively high TRL, favorable overall characteristics, and absence of significantly low scores regarding the criteria assigned high priority by the decision-makers, in comparison to other energy supplies.
However, the validity of the presented results is reduced due to several factors. These include the reliance on assumptions about alternative energy supplies, a limited number of interviewees, and the sensitivity to uncertainties about future developments. Nevertheless, this study shows that the use of this method can provide insights into complex decision problems regarding future energy supply choices. Also, the study identifies a range of attractive energy supplies, with methanol used in an ICE ranked as the most suitable option. These high-ranking energy supplies can be an interesting subject for further studies.
... Read more

The demand of offshore wind energy has increased enormously in the last decade, and continues to do so in the foreseeable future. The monopile will remain the most important foundation structure. There is however not yet a durable solution for its main disadvantage; the under water sound radiation during installation. In this report a new, silent installation method is therefore explored: screwing monopile into the ground. In this thesis the interaction between the monopile and soil is explored, along with the addition of a screw thread. Based on this the driving requirements are determined. Then a possible driving mechanism is shown, considering the driving power, connection between the ship and the monopile and driving equipment. Lastly, the implications of the logistics is explored. ... Read more

Seaport operators are becoming more environmentally conscious and are looking to electrify their terminals to reduce their greenhouse gas emissions. This leads to higher energy-related costs and more congestion on the electricity grid. This thesis investigates the potential of demand response as a viable strategy to reduce energy-related costs. By modifying operational planning, energy consumption could be deferred from peak to off-peak hours, resulting in cost savings. Different potential ways within the terminal to provide demand response are identified. I propose a two-stage stochastic mixed-integer programming model to optimize operations planning, incorporating energy-related costs. Both energy demand and supply uncertainties are accounted for, exploring various scenarios for vessel arrival times and fluctuating electricity prices. The model is decomposed using a progressive hedging algorithm. Operational aspects considered in this model include vessel arrival scheduling, temperature control of refrigerated containers, allocation of handling capacity across quay cranes, yard cranes, and automated guided vehicles, as well as a charging schedule for the automated guided vehicles. A case study of the Altenwerder container terminal in Hamburg was conducted to test the model. Preliminary results suggest potential cost savings in the range of 12.0-13.2 % with a varying electricity prices based on wholesale market rates. Furthermore, it was found that stochastic modeling improved the solutions found of up to 20.6 % compared to a deterministic model. These findings underscore the substantial potential of demand response strategies in the context of container terminal operations ... Read more

Ambitions to limit climate change are incentivizing the expansion of renewable energy. In particular, offshore wind energy is expected to grow rapidly. To harness the full potential of existing as well as prospected offshore wind farms, the limited capacity of the internal cable network of the offshore wind farm, called the collector system, should be efficiently used.

The operation of the collector system during cable outages presents significant potential in this regard. Currently, during these outages, a conservative approach is taken that under-utilizes the capacity of the collector system and consequently limits power production excessively. The available headroom of the system can be unlocked by optimizing the power routing and turbine setpoints. This optimization problem is the topic of the MSc Thesis, carried out
within Vattenfall.

Two novel optimization-based rerouting and setpoint decision frameworks are developed for collector systems with arbitrary topologies: an open-loop control strategy and a receding horizon control strategy.

The open-loop control strategy assumes that the network can only be reconfigured at the beginning of the outage. It is formulated as a mixed-integer linear programming problem, in which the cables are modeled as binary control variables and the setpoints as continuous control variables.

The receding horizon control strategy is deployed in real time, leveraging cable temperature measurements and power forecasts to derive optimal control actions dynamically. Dynamic thermal rating is applied, which entails that the power flows are constrained based on the cables’ temperatures rather than on a static rating. The resulting control strategy is formulated as a mixed-integer quadratically constrained programming problem.

A case study is performed to compare the performance of the developed strategies to existing strategies. Simulations concerning seven occurred cable outages at an offshore wind farm show an average increase in power production with respect to the industry control strategy of 0.82% for the open-loop control strategy and 4.2% for the receding horizon control strategy.
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Hybrid technology can significantly reduce fuel consumption and emission for vessels that have high power demand peaks followed by long periods of low loading. Hybrid technology refers to powertrain layouts that consist of hybrid propulsion and/or hybrid power supply. Advanced energy management strategies (EMS) are required to make optimal use of these available power resources. In this paper it is investigated how much fuel consumption reduction can be achieved by applying a causal, real-time equivalent consumption minimization strategy (ECMS) to a hybrid propulsion and hybrid power supply plant with a power load forecasting scheme, for a case study vessel: The Holland-class offshore patrol vessel. The forecasting tools evaluated are Linear regression, moving average, ARIMA and recurrent neural networks (RNN). The RNN outperformed the other methods and is able to predict the power demand for up to 48 seconds, while maintaining a mean absolute percentage error of under 5%. An optimization-based controller is combined with an ECMS approach which assigns an equivalent consumption cost to the battery. The controller is able to identify the power split for the hybrid propulsive system, and the power split for the hybrid power supply. A simulation proved that 0.77% fuel savings are achieved with a 400 kW battery, compared to a no-battery scenario. Fuel savings could not be proven for the EMS with a control horizon of 48 seconds, leveraging power predictions supplied by the RNN, due to limiting factors. The limiting factors are the combination of the small control horizon, the limited battery capacity compared to the overall power demand and the limited tuning of the ESFC curve. ... Read more

As a result of the need for higher productivity ship-to-shore container cranes, seven concepts are composed that can simultaneously transfer 4 Twenty Foot Equivalent Unit containers. All concept can be built on a standard ship-to-shore crane structure. These concepts are based on working principles found in (patent) literature. The concepts are compared based on multiple objectives, after which one concept is chosen to realize a concept design. A ship-to-shore crane with two trolleys turns out to be the most suitable concept. The two trolleys consist of a rope towed trolley and a semi rope trolley, which are combined with a continuous rope support system. The design of the trolleys is based on an existing trolley. For all wire ropes to run adjacently, the sheave diameters and positions on both trolleys deviate from the existing trolley. The sheave positions have consequences for the trolley frame design. To validate the adjusted trolley frames, a finite element analysis is performed. ... Read more