The integration of nuclear propulsion into civilian maritime vessels offers a promising pathway towards low‑emission, long‑endurance operations, particularly for energy‑intensive offshore applications. High‑Temperature Gas‑Cooled Reactors (HTGRs) are well suited for such use due to their inherent safety characteristics and high thermal efficiency, but their limited load‑following capability restricts their ability to directly meet the highly dynamic power demands of ships. This thesis investigates how a hybrid energy storage system (ESS), combining thermal and electrical storage, can be sized, configured, and integrated to enable safe and efficient HTGR‑based maritime propulsion.

A dynamic, system‑level model is developed in Python to represent the interaction between an HTGR, an intermediate molten‑salt loop, a steam Rankine power cycle, auxiliary diesel generators, and hybrid energy storage. Reactor ramp‑rate constraints, thermal inertia, turbine efficiency limits, and storage charge–discharge constraints are modelled. A 14‑day operational load profile of the deep‑sea mining vessel Hidden Gem is used as a case study to quantify power mismatches and storage requirements. A comprehensive sizing study is performed for a range of thermal and electrical storage capacities, evaluating feasibility based on unmet load, dumped energy, diesel fuel consumption, and operational stability.

The results demonstrate that a hybrid ESS substantially improves operational flexibility, eliminates unmet load across feasible configurations, and reduces diesel fuel consumption compared to a non‑storage baseline. Thermal storage primarily buffers medium‑timescale reactor ramp limitations, while electrical storage absorbs fast transients and residual mismatches. The findings highlight that optimal ESS sizing strongly depends on the temporal structure of the ship’s load profile, rather than peak demand alone, and provide a structured methodology for hybrid ESS integration in future nuclear‑powered vessels. ... Read more

The maritime sector faces growing pressure to decarbonize, driven by increasingly stringent regulations and long-term climate targets. Among zero-emission propulsion options, hydrogen fuel cell–battery-electric systems have emerged as promising solutions, particularly for short-sea shipping. However, their large-scale adoption remains limited due to high fuel and investment costs, insufficient infrastructure, safety considerations, and significant uncertainty regarding lifetime economic performance.

A key challenge in hydrogen-fuelled ship design is the strong coupling between energy system sizing, operational strategies, and external influences such as weather and market conditions. In the literature, these aspects are often treated separately, focusing either on control of fixed designs or on system sizing under simplified operating assumptions, which can lead to economically suboptimal or operationally infeasible solutions. This thesis addresses this gap by developing a unified design-operation optimization framework that minimizes lifetime cost while accounting for technical, operational, and regulatory constraints under realistic operating conditions.

This thesis focuses on conceptually retrofitted cargo vessels, where conventional diesel propulsion is replaced by a fuel cell-battery electric configuration. Lifetime performance is evaluated using a techno-economic framework based on a Net Present Value (NPV)-based cost formulation, which captures capital expenses, operational costs, component degradation, and replacement over the remaining service life of the vessel. The framework is used to compare the diesel baseline and hydrogen retrofitted configurations in terms of system design and lifetime cost under consistent operational assumptions.... ... Read more

With rising global emissions and the maritime sector accounting for approximately 3% of total greenhouse gas emissions, the International Maritime Organization (IMO) has set a target to achieve net-zero greenhouse gas emissions by 2050. To meet this goal, the shipping industry requires the development and adoption of new propulsion technologies. In this context, nuclear energy has emerged as a promising option due to its very high energy density, ability to deliver consistent power independent of external conditions, and zero operational GHG emissions. Despite its advantages, nuclear propulsion has seen limited commercial adoption, with most existing applications confined to naval vessels.

To address this gap, this thesis investigated the feasibility of integrating a nuclear reactor into the power generation and conversion system of a high-energy-consuming commercial vessel with dynamic positioning capability.
A nuclear reactor coupled with a cascaded Brayton cycle was selected as the power source. Based on the vessel’s power profile, two reactors and an additional battery pack were determined to be necessary. A failure mode and effects analysis identified critical components, informing the development of two design configurations: one with partial redundancy and one with full system independence. Both achieve comparable thermodynamic performance. Integration aspects, such as power distribution architecture, physical layout, and equipment placement, were addressed lastly to ensure feasibility.
The study concludes that nuclear retrofitting is viable at a conceptual level, pending further engineering and safety development. ... Read more

Renewable energy introduces (seasonal) imbalances between the supply and demand, contributing to net congestion on the electric grid. Seasonal energy storage offers a potential solution by shifting excess renewable generation to periods of shortage. This research investigates the feasibility of using room temperature metal hydrides for seasonal energy storage in the built environment, the pilot: Urban Energy Island project of the housing corporation deltaWonen as a case study. 40 apartments will be part of an innovative energy system to become 80\% autarkic while being limited to 40 kW of available grid capacity.
To evaluate this concept, a system-level model predictive control (MPC) strategy was developed to coordinate the energy supply and demand across a daily battery, the electric grid capacity, a PEM electrolyser, and a PEM fuel cell, interconnected via a TiFe metal hydride storage system. Waste heat from the different components is also recovered and utilised. After calibrating with ten-year average data and verifying using verification tests, the model was tested for the years 2013 and 2015, including extreme cases. Beyond technical performance, the research also asses safety, cost, reliability, environmental impact and spatial feasibility.
The results show that while the current size of the metal hydrate storage is insufficient to cover the seasonal energy demand, it is effective in supporting shorter-term shortages, such as during a dunkelflaute. The system also shows potential for modular scaling. Future research should explore integrating dynamic energy grid prices into the MPC formulation and implementing a higher-level control layer for strategic long-term energy planning. ... Read more

This paper presents the design and modelling of a next-generation nuclear-powered mother ship capable of serving as a self-sustaining refuelling hub for unmanned maritime vehicles. A 140m vessel equipped with a 130 MWth Very High Temperature Reactor was modelled as an integrated energy system that converts nuclear heat into synthetic diesel (F-76), through high-temperature electrolysis, direct air capture, and Fischer–Tropsch synthesis. An Energy Management System (EMS) was developed to coordinate power balance onboard. The EMS was extended with a mixed-integer linear programming layer, allowing fleet-wide optimisation of refuelling and mission timing for up to six unmanned surface vehicles. Mission scenario simulation results show that the nuclear mothership can maintain long-term autonomous operations with minimal external fuel dependence, providing aself sustaining alternative to conventional refuelling operations. ... Read more

The devastating effects of climate change are becoming more evident each day. We are running out of time, and our best collective effort is needed to revert the situation and ensure a sustainable and healthy future. Renewable energies are a key enabler for such a future. Wind energy has attained remarkable progress in the last decades, and the growth required to meet future net-zero scenarios is extraordinary. Wind turbine technology is rapidly evolving towards larger rotors and power ratings, resulting in much higher torque density demands for the drivetrain in general and the gearbox in particular. Maintaining or even improving gearbox reliability with increasing torque density demands is proving to be challenging. Accurate knowledge of the mechanical loads of wind turbine gearboxes has become essential for modern highly loaded gearbox designs with significant dynamic interactions. The contribution of this dissertation can be summarized by its goal: to develop a method to measure dynamic mechanical torque in geared wind turbines. A key requirement was set to enable fleet-wide implementation to monitor torque throughout the complete service life of the wind turbines. This dissertation proposes a method based on strain measurements on the outer surface of the static first-stage ring gear that overcomes the main drawback of traditional methods. A series of experiments are presented, ranging from proof-of-concept tests conducted using gearbox test benches to an extensive field validation campaign. These experiments have advanced the technology readiness level and demonstrated the accuracy and robustness of the proposed method, which is now deemed ready for commercial implementation. Future research should explore improving drivetrain loading using dynamic mechanical torque measurements with novel data-driven control strategies. Additionally, recursively tracking operational deflection shapes over time is recommended for fault detection. ... Read more

The development of shipboard DC power systems promises significant operational and economic benefits but faces major challenges in primary distribution, protection, and power scalability. As DC technology continues to mature, many aspects of shipboard implementation remain insufficiently defined to guarantee both safety and efficiency. Current regulatory standards are incomplete, and protection strategies often rely on outdated or inadequate frameworks. Unipolar and bipolar bus architectures each offer application-specific advantages, and the strategic placement of power electronics opens new possibilities for centralized and distributed switchboard designs. However, protection architectures still face limitations: breaker-based approaches rely on slow fuses, mechanical circuit breakers, or emerging solid-state circuit breakers, while power electronics–based protection, embedding protective functions within converters, remains underdeveloped. Furthermore, the low production rate of vessels and the varied power demands across applications often force designers to employ commercial off-the-shelf converters, raising challenges in modular topologies, scalability, and overall protection strategy.

This research addresses protection challenges through a multi-stage investigation into shipboard DC systems and power electronics for DC protection. First, a
use case–based categorization of short-circuit events in primary DC systems is proposed. A detailed fault inventory is compiled using a reference 5 MW superyacht model, providing simulation-based short-circuit data for diverse operational scenarios. The study contributes: (1) a comprehensive short-circuit inventory, (2) a qualitative fault categorization, and (3) design recommendations for power converters in shipboard DC systems. This work emphasizes that systematic fault classification is critical to understanding the impact of different short circuits and to guiding both protective device design and regulatory evolution.

In parallel, the thesis advances the state of the art in DC fault protection hardware. A high-speed solid-state circuit breaker (SSCB) is developed, integrating
a latching current limiter to prevent unnecessary tripping during transient overcurrents. Supported by a custom gate driver and controller, the SSCB prototype
achieves a clearing time of approximately 200 ns, substantially reducing system stress during faults. Both SPICE simulations and experimental tests confirm its
capability to properly operate under diverse fault conditions while requiring low complexity upgrades.

Finally, a proof-of-concept DC–DC converter with embedded protection is demonstrated. The proposed protection module, based on the electronic capacitor concept, is integrated into a 10 kW bidirectional LLC converter. Placed in series with the DC-link capacitor, the module significantly reduces processed power and conduction losses compared to conventional series-breaker configurations. Experimental validation confirms that the approach is compatible with fuse-based selectivity strategies while offering rapid fault isolation and reduced design complexity.

Collectively, this thesis provides a comprehensive framework, from system-level fault categorization to device-level protection design, supporting the safe and scalable adoption of shipboard DC systems. The proposed solutions and prototypes contribute to addressing essential protection challenges, favoring the widespread adoption of DC systems in various applications, by offering more efficient, compact, and safe DC systems, which ultimately play an important role in the transition of energy for transportation in general. ... Read more

To reduce the greenhouse gas emissions of ships, hybrid power systems are becoming more common. Hybrid systems combine power generation with energy storage. The energy storage enables the power generating components to run at more efficient operating points. A well known combination is that of a diesel genset and a battery. The ideal combination of the type, size, and amount of power system components depends highly on the operating profile of the vessel. However, this operating profile can vary greatly between voyages, or during the lifetime of a vessel, thus changing the ‘ideal’ power plant. A modular power system (MPS) can provide the solution: a reconfigurable power plant, where components can be added, removed, or replaced.
To control the power-split between the different components an energy management system (EMS) is required. Most EMSs are designed and optimized for a single power plant configuration. This means they are not capable of dealing with an MPS. For this thesis an EMS was developed which is capable of dealing with an MPS: an MPS EMS. The developed EMS was made for ships with electric propulsion. An additional requirement was for the EMS to be real-time capable, so it can be used outside of a simulated environment, i.e. in a real ship. The objective of the EMS would be to minimize fuel consumption.
It was investigated which EMS control strategy would be suited for an MPS EMS. The equivalent consumption minimization strategy (ECMS) combined with the dual decomposition method was found to be suited for this purpose.
The developed EMS can automatically adapt all parameters responsible for stable control of the system. It does this based on the properties of the installed components. Most important of these properties are: minimum and maximum power output, maximum ramp-rate, and the efficiency curve.
The EMS was tested with four different combinations of installed components, and two different operating profiles. Additionally, the effect of a component failure during a voyage was tested. A rule based (RB) EMS and a mixed integer linear programming (MILP) global optimization were used as benchmarks for the fuel consumption. The results show that the developed EMS is capable of controlling various power plant configurations in different conditions, while keeping all components within their allowed operating ranges. For one of the tested operating profiles the fuel consumption using ECMS was 1.9-4.0% higher than when using the global optimization, which is comparable to the results found in literature. However, for the other tested operating profile the developed EMS was outperformed by even the RB EMS, by 1.1-2.1%. This was caused by inaccuracies of the approximation used for the efficiency curve of the gensets. In the simulations where one of the gensets fails during the voyage the EMS was able to automatically adapt to optimize fuel consumption using only the remaining components. Fuel consumption did increase slightly compared to no failures, as expected.
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Today’s necessity- and goal to reduce carbon emissions in tandem with finite fossil resources and rising oil prices, demand for an alternative and cleaner energy source to power the world dredging fleet. In parallel, recent research in naval architecture iterates the potential role for nuclear-based propulsion on board of ’energy-intense’ merchant vessels (approx. 20 MWe+ installed power) [16][20][23]. Powering a (large) trailing suction hopper dredger (30.000m3+) by an on-board small modular nuclear reactor would cut direct greenhouse gas emissions by 100%.

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

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

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

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

The Dutch Ministry of Defence (NLMoD) has stated the goal of reducing dependency on fossil fuels by at least 20% by the year 2030 and at least 70% by the year 2050 compared to the year 2010. Research in the NLMoD explores the possibility of changing diesel-fuelled vehicles and weapon platforms to alternative forms of energy such as electric or sustainable fuels. In these projects, the focus is on (part of) the vehicle or energy source itself, but the impact on the Military Supply Chain (MSC) is missing.

This research has developed a Mixed Integer Linear Programming model that can be used to gain insight into the impact of the energy type of tactical vehicles and weapon platforms on the MSC and therefore is able to see what energy type has the lowest impact on that MSC. The impact on the MSC is measured by minimizing the refuel time, number of supply trips, and CO2 equivalent emissions. The model can provide insight into what the minimal requirements of potential energy carriers and conversion devices should be in order to have a similar or better impact on the current diesel MSC. The model is based on the current supply chain of the NLMoD and is expanded with the use of APUs for vehicles, energy generation at Nodes, the use of small supply trucks as energy buffers, compatible supply material, and longer self-sufficient times. Combinations of these are looked at in different policies.

Results show the trend that energy types with lower CO2 equivalent emissions have higher refuel time and number of supply trips. An exception to this is HVO and HVO-electric series hybrid, which also have the least impact on the MSC. Energy types such as hydrogen and electric require huge improvements in energy density, fill speed, and FTW efficiency to come close to the results of current diesel. ... Read more

Electrification of numerous end-users is a worldwide trend to address climate change, according to the International Energy Agency. This trend has also reached container terminal operators. Currently most of the ship-to-shore cranes employed are electrified, leading to an increase in the required electrical power demand and to an increase in the volatility of the electrical power demand of container terminals. As a result, the contractual power demand charged by the grid operator, based on the maximum required power demand (peak power) at any moment in time, is upscaled, leading to additional costs for the container terminal operator. However, the highest required power demand values occur infrequently, leading to significant expenses for a resource that is rarely utilised. By implementing a peak shaving strategy, the peak power can be reduced, leading to a decrease in the contractual power demand related costs. Nevertheless, it is crucial to minimise the impact of the specific peak shaving strategy on the productivity of a container terminal to actually derive economic benefits from its implementation.

The aim of this study is to develop operational policies that effectively maintain productivity for a cluster of six ship-to-shore cranes under increasingly restrictive peak power limitations. A discrete event simulation approach was employed for evaluating the operational and economic impact. In total four policies were developed, two according to the `who fits is served' approach (policy 0 and policy 1) and two according to the `priority based' approach (policy 2 and policy 3). In the first approach the initiation of a movement only depends on the power availability, while for the second approach the initiation of a movement depends on the power availability and the urgency of the movement in terms of productivity. Moreover, for both approaches one policy allows only one kinematic profile (policy 0 and policy 2) and one policy allows varying kinematic profiles (policy 1 and policy 3). A metaheuristic was employed to find near-optimal adapted kinematic profiles.

The findings of this study suggest that the established `priority based' approach is more effective than the `who fits is served' approach in maintaining productivity under increasingly restrictive peak power limitations. When combined with the allowance of adapted kinematic profiles (policy 3), this strategy achieves the most cost savings. Policy 3, has been shown to reduce the contractual power demand related costs by 53\% compared to the baseline scenario, which is the greatest recorded reduction of all created policies without adversely affecting the ship-to-shore cranes' productivity.
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Green hydrogen plays an important role in the energy transition. It can function as a storage medium, as well as a replacement for fossil fuels in transport or high-temperature heat processes. However, the economic feasibility of electrolysers has proved to be a problem. Even though a lot of research has been done to the electrolysis technology, very few research has been done to the implementation of an electrolyser.

For this research, a physical model of an electrolyser has been developed, as well as an Energy Management System (EMS). For this system, trading strategies for electricity markets have been developed. By trading on the imbalance and day ahead market, the contribution margin (hydrogen revenue minus electricity costs) has been significantly increased by over 27%. Seasonal hydrogen storage in salt caverns has proven to be a promising solution for producing more hydrogen and increasing revenue, depending on the storage costs that are applied. A Battery Energy Storage System (BESS) has been added to the system for its competence in dynamic behaviour on the electricity markets. For the addition of a BESS to an electrolyser, no conclusive proof of the benefits for the economic viability of green hydrogen has been found. ... Read more

Due to the growing demand for offshore wind energy and the increasing wind turbine sizes, a shortage of capable installation vessels is anticipated by 2024. Consequently, the utilisation of heavy-lift vessels, previously not employed for bottom-founded or floating offshore wind turbine installations, may become imperative to realise the offshore wind project pipeline. Therefore, this study analyses the technical and economic feasibility of installing floating wind turbines with the largest construction vessel in the world named the Pioneering Spirit. For this, the concept development stage of the systems engineering method was applied, consisting of three successive phases. Firstly, in the Needs Analysis phase, valuable insights regarding the operational environment were obtained, resulting in operational requirements for the concept design. Secondly, in the Concept Exploration phase, these requirements were used for generating multiple alternative concept options after which the most promising concepts were selected for further analysis through a trade-off analysis. Lastly, in the Concept Definition phase, the technical feasibility, workability and economic feasibility were evaluated for the selected concepts. The technical feasibility was assessed by creating storyboards for the different installation procedures, determining the stability of the barge named the Iron Lady for different load cases and providing technical descriptions of performed operations and required equipment. Furthermore, the workability was estimated by comparing statistical wave and wind data with the environmental limits for various operations obtained through literature, previous projects and a motion analysis model. Subsequently, with the storyboards and workability results, the economic feasibility was determined with a model that included estimations of the vessel and fuel costs for constructing a reference wind farm located at a variable distance to shore. Ultimately, it was found that Spar- and TLP-type floating wind turbines are of most interest for the concept design and that the Pioneering Spirit is in principle capable of installing the corresponding pre-assembled foundations and wind turbines relating to a capacity of 15 megawatt with a single-lift operation. Furthermore, this research gives valuable insights that extend beyond the initial scope of this paper. Since the performance implications of the selected concepts related to the workability assessment and economic feasibility study can directly be linked to specific design choices and limitations. This, in combination with the exploration of floating wind turbine installation with alternative lifting equipment, can be used to provide recommendations for future designs of purpose-built vessels in this sector. Finally, the methodology used in this study could be applied to evaluate the feasibility of other potential concepts for deployment in this area. ... Read more

Chain belt conveyors have become a popular choice for transporting materials in diverse industries. The primary driving force behind these conveyors is the gearmotor, which is composed of an electric motor and a gear unit. The industrial electric motor market is estimated to be 21 billion USD and consumes up to 70\% of the electricity by the industry. However, research on chain belt conveyors systems remains limited, leading to poor maintenance strategies and inadequate understanding of their efficiency. The aim of this paper is to develop a digital twin for condition monitoring, applicable to industrial gearmotor-driven chain belt conveyor systems. To achieve this, the current state-of-the-art and industry practices were analysed, focusing on SEW Eurodrive as a representative for industrial industry. A literature review was conducted to explore predictive maintenance, digital twins and condition monitoring in the context of chain belt conveyors. Consequently, this has culminated in the development of a novel chain belt conveyor model, based on fundamental mechanical analysis of the chain belt conveyor, while also acknowledging the limitations associated with industrial settings. In order to accomplish this objective, parameter estimation was performed for system identification using data collected from physical chain belt conveyor systems. Additionally, various methods have been proposed for anomaly detection, which include the utilization of estimated parameter thresholds, frequency domain analysis, statistical residual analysis and the assessment of the transport loss factor. Verification and validation have been performed using data from a chain belt conveyor system. Eventually, a case study was conducted with promising results in terms of robustness and accuracy. In the industrial setting, dynamic weighing attained a benchmark accuracy of 95\%. Further research, with data over longer periods of time, is required to establish degradation patterns and optimize the model for broader applications. ... Read more

This research analyses the potential of Electrical Signature Analysis (ESA) as a means for condition monitoring of mechanical defects of induction motor driven thruster assemblies in the maritime industry. This is done by measuring the three phase current and voltage of three thrusters, with different health conditions, of a marine vessel sailing at different speeds. In this data, the mechanical behaviour of the machines is detected by plotting the frequency spectra of various electrical parameters, such as complex current and torque. After successfully identifying mechanical behaviour and defects, a suggested approach for the implementation of ESA as a means for condition monitoring is presented. ... Read more

The process of salvaging wrecks can be costly and time-consuming, making it crucial for salvagers to select the appropriate technique(s) and accurately estimate the total costs to minimize expenses and optimize efficiency. Salvagers typically use their expertise, experience, and data from previous projects to make these estimates. Diamond wire cutting is a material-cutting technique with much potential for use in wreck salvaging. However, a previously conducted literature review revealed a lack of sufficient information in the existing literature to determine the cutting rates of diamond wire used in wreck removal, indicating a gap in current knowledge. A deeper understanding of the technique is needed to evaluate salvagers' capability of cutting diamond wire in wreck removal. Therefore, the primary focus of this paper is to provide a method to estimate the cutting rate of diamond wire when used in wreck removal. The effect of wire speed, normal load on the workpiece, various materials encountered in wreck cutting, different geometries, and environments on cutting rate have been investigated. Filling this knowledge gap is of particular interest to Boskalis, as they currently have limited knowledge and experience with diamond wire cutting, making it challenging to estimate costs. Additionally, research into wreck removal techniques is socially significant, as the ability to remove wrecks efficiently and with minimal environmental impact is crucial. Therefore, this thesis aims to provide a deeper understanding of diamond wire cutting in its application in wreck removal.


Main factors determining the potential of a technique for removal include the total duration of removal, the required assets, and the associated risks. The primary focus of this thesis is to develop a method to estimate the cutting rate of diamond wire when used in wreck removal. The cutting rate will be predicted using the Archard wear equation, which requires an unknown coefficient ($K$) that can be determined through experiments. A real-world set-up with diamond wire was used to obtain data.

The results show that for the steels and cast iron in this survey, Archard's assumption that the wear volume is inversely proportional to hardness is not supported. Consistent with Archard’s equations, the wear volume has been found to be proportional to normal load, sliding distance but independent of speed within the range of tested conditions. As such, the Archard wear equation can be applied to the materials tested, but its applicability to materials that differ significantly from those tested is uncertain. Furthermore, results show that cooling significantly impacts both wire life and cutting rate. Specifically, fully submerging the workpiece resulted in a
XX\% improvement in the cutting rate as compared to spraying with coolant. It should be noted that these results were obtained under controlled conditions where normal load, wire speed, and cutting angle were kept constant, and proper cooling was possible. These operational parameters may vary in real-world scenarios, such as cutting through a shipwreck, leading to deviation from the predicted cutting rates. ... Read more

Climate change due to greenhouse gas emissions is prompting the IMO to reduce emissions by 80% by 2050. This thesis focuses on designing modular propulsion systems for mid-speed sailing vessels to meet these regulations. It designs a framework to generate and swiftly evaluate propulsion system designs on the basis of five performance indicators: Weight, Volume, Life Cycle Costing, Modularity and Emissions. Additionally, the framework is proven on the basis of a case study, which results in a modular concept. ... Read more

The company H2 Marine Solutions has designed a zero-emission hydrogen powered boat. This boat is compared to its fossil fuel counterpart more than twice as heavy. The reason for this is that the system components that are used in the hybrid powertrain of the hydrogen powered boat are heavier. The main question of this research is: How can we establish the optimal energy and power of the system components of a hybrid power system with optimal energy management for a zero-emission hydrogen powered boat for different operational profiles? This results in a sizing and control optimization problem. Because these two problems are coupled this is a multi-objective double-layer optimization problem. The most popular strategy to solve this problem is with the control problem nested in the sizing problem \cite{Hybrid-ship}. The most popular algorithms to solve these problems are evolutionary algorithms.

Unfortunately due to the complexity of these algorithms and due to lack of time the sizing and control problems are solved separately in this research. First, the system components of the plant are described and modeled. The components that are modeled are the battery, the fuel cells, and the DC/DC converter. To find the optimal energy management strategy an online optimization strategy is used. This is done because the problem is solved in real-time than and could be used in a real application. The strategy that is chosen to solve the control problem is the Equivalent Consumption Minimization Strategy (ECMS). This strategy translates the electrical energy from the battery into equivalent hydrogen consumption. For every timestep, the equivalent consumption is minimized by the ECMS. Because there are different variants of ECMS three of these variants are discussed and compared in the research. Also, two rule-based energy management strategies are compared. The sizing problem is described by linear equality and inequality constraints. The problem is solved by the Linprog function in Matlab. The objective of the sizing problem is to minimize the weight of the system components. The input in the sizing problem is the energy and power demand of the most energy intensive operational profile. After solving the sizing and control problem the results are combined and the different operational profiles are used as input to show the robustness of the optimization.

The three different energy management strategies all minimize the instantaneous equivalent consumption but show different behaviors when controlling the system components. The optimal energy management strategy is the Smooth Adaptive Penalty (SAP)-ECMS. With this controller, the fuel cells work on a steady operating point and ramp up and down the output power smoothly when necessary. Due to this behavior, the average efficiency of the fuel cell is the highest, and the hydrogen consumption is the lowest compared to the other controllers. The results of the sizing problem show that the weight will decrease when a bigger fuel cell is used in combination with a smaller battery. The consideration between a bigger fuel cell and a smaller battery is a consideration between lower weight and more hydrogen consumption. When a bigger fuel cell is used it is recommended to implement an optimal energy management strategy such as the SAP-ECMS to control the output power of the system components. This is preferable above a rule-based controller which can not find the optimal operating point at all timesteps. Even better energy management strategies may exist or could be made by combining different ECMS's. When the sizing and control problem are solved in a nested strategy more accurate results could be achieved. ... Read more

With the rapid advancement of technology, we are moving towards a society that is increasingly driven by computer intelligence. At the same time, we are facing pressing environmental issues that are pushing us towards cleaner solutions. One industry that is heavily influenced by these two factors is the automotive industry, where autonomous electric vehicles are gaining more popularity. Audi AG, one of the biggest car manufacturer companies, is now trying to take a step forward in this market by implementing two low-voltage energy sources into the system to improve automation features. The main obstacle to the introduction of these energy sources is the strong influence that temperature has on them. Both high and low temperatures are detrimental to the battery's lifespan and performance and, in extreme conditions, they may completely impede the energy source from supplying energy or lead to thermal runaway. Therefore, effective thermal regulation of the energy source is fundamental to ensure battery availability and enhance efficiency. The objective of this research is to develop a new thermal regulating system for low-voltage energy sources in autonomous electric vehicles. ... Read more

A major transition became necessary for the maritime industry to meet the IMO’s targets for mitigating the carbon footprint of the sector by at least 50% by 2050. One of the promising methods to lower the emissions is the ship's hybridization. An enormous increase in pilot and demonstration projects for that purpose is being observed. This research was contacted through the involvement of TU Delft in such a project called the Implementation of Ship Hybridisation.

The design and optimization of hybrid propulsion systems is a complex and challenging task due to the different power sources involved and the dependence on the energy management and control. The physical system and the control algorithm should be designed in an integrated manner to obtain an optimal system design. This study applies a multi-objective double-layer optimization methodology to optimize the sizing and energy management of a hybrid ship propulsion system to be installed on a Crew transfer vessel. A proposed hybrid topology which combines diesel engines, batteries and fuel cells is considered. The proposed approach incorporates the development of fuels and electricity prices as well as the investment costs of the system’s components as an uncertainty element. The introduction of emission reduction measures such as carbon tax was also considered in the study. Future trajectories for the relevant uncertainties were developed and incorporated in the optimization methodology to provide decision-makers with a more realistic picture of the solution space.

The analysis of the optimization results was based on the Total cost of ownership (TCO) and the emission reduction potential of the optimal designs produced by the optimization methodology. The results show that instead of choosing a hybrid propulsion system for the vessel under study, an all-electric propulsion system which is based entirely on batteries and fuel cells is the most economical and environmentally friendly option. Incorporating diesel engines has a negative impact on the operational expenditures of the system in the long term. A fully electric propulsion system would require a larger initial investment from the ship owner, but it would pay off over the course of the ship’s remaining useful life.

This research can be used as a reference to base the decision of the stakeholders on choosing a new propulsive system for their vessel. The parameters of the optimization methodology can be easily changed to explore more options and expand the design solution space if this thesis’ results don’t satisfy the shipowner. In addition, it is suggested that a professional user interface designer be involved in the development of a real life decision support tool, incorporating the multi-objective optimization methodology.
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