To address the growing need for sustainable aviation, hydrogen fuel cell technology is being explored as a promising alternative to conventional kerosene-based propulsion systems. Compared to hydrogen combustion, hydrogen fuel cells offer a significant environmental advantage by producing zero nitrogen oxides (NOₓ) in their exhaust. For commercial viability, aircraft design must optimize both range and payload, which in the context of hydrogen fuel cell propulsion translates to maximizing system efficiency and minimizing propulsion system weight. Achieving these objectives requires accurate and flexible system modeling tools.

This thesis focuses on the development of a new hydrogen fuel cell system modeling library in Modelica, named AeroFCS. The library is a joint effort between zepp.solutions and Delft University of Technology and is designed to be compatible with the existing DeSimECS Modelica library developed by the Faculty of Aerospace Engineering. The choice of Modelica, an acausal modeling language, enables flexible system configurations by allowing input-output modifications without component model adjustments. The AeroFCS library includes a custom fuel cell model and a validated humidifier model. These are integrated with compressor, intercooler, and turbine models from DeSimECS to simulate a complete fuel cell air supply system. Additionally, a verified two-phase medium model is used to simulate humid gas properties. A Python-Modelica interface is developed to facilitate simulation post-processing and to support future system optimization studies. System simulations are conducted under specific environmental conditions and across a range of fuel cell operating pressures and currents. Operational maps are generated to assess compressor pressure ratios and mass flow rates. These maps help identify regions of optimal performance by plotting system efficiency and net power between the surge and choke lines of the compressor. Results indicate that the highest efficiencies are achieved at high pressure ratios, close to the surge limit of the compressor, for any given system power.

The AeroFCS library offers a foundational tool for simulating and optimizing hydrogen fuel cell propulsion systems, and future work will focus on improving model fidelity and increasing model functionality.

The maritime industry faces increasing pressure to reduce its environmental impact, particularly through the reduction of greenhouse gas emissions. This thesis investigates the feasibility and technical implications of operating large, low-speed, two-stroke marine engines on hydrogen using low-pressure direct injection. The study addresses the lack of specialized combustion models for hydrogen in large marine engines by developing a tailored in-cylinder thermodynamic combustion model.

A comprehensive literature review highlights hydrogen's unique combustion characteristics, such as high flame speeds, low ignition energy, and wide flammability range, along with associated challenges like pre-ignition, knocking, and NOx emissions. Existing combustion strategies and injection technologies, particularly those adapted from natural gas-fueled engines, are evaluated for their applicability to hydrogen combustion.

The developed combustion model integrates a Seiliger cycle representation enhanced by temperature-dependent thermodynamic properties. It systematically assesses the effects of hydrogen combustion on key engine parameters, including pressure rise rate, peak cylinder pressures, and temperatures, under various operational scenarios. The results highlight the importance of combustion phasing and air-excess ratios in managing hydrogen combustion characteristics, indicating that careful optimisation of injection timing and combustion strategy is crucial to ensure safe and efficient engine operation. Although the model reveals risks associated with aggressive combustion scenarios, such as exceeding mechanical design limits due to high peak pressures, it provides a structured framework for identifying realistic operating conditions for hydrogen LPDI combustion.

This research thus offers critical insights into the technical feasibility and practical limitations of hydrogen combustion in large two-stroke marine engines, contributing valuable guidance for future development and experimental validation efforts.

A significant push toward sustainability has emphasized the need to make all vessels as energy efficient as possible. Close attention must be paid to the performance evaluation of the vessel’s main energy consumer, particularly the engine. Moreover, prioritizing the efficient operation of the engine is essential for maintaining the vessel’s operational safety. Engine performance evaluation has been conducted using various methodologies, based on either field testing data or physical and data-driven models. This research focuses on developing a condition monitoring model that is effective even with limited data availability, highlighting the correlation between subsystem degradation and its impact on the overall underperformance of the engine. The literature review examines potential methods for condition monitoring of marine diesel engines, with a focus on their modeling purposes. These methods are classified based on their theoretical foundation: White-box models, which are based on first principles, and Black-box models, which rely on the interrelationships between input and output parameters using available mathematical tools. Additionally, the literature discusses Grey-box models, which combine physics-based principles with data-driven approaches. The modeling purpose of the methods analyzed is identified as either parameter estimation or fault detection and isolation, depending on the available data and the chosen methodologies. To achieve the objective of this thesis, a structured model development process is formulated. This process begins with defining the available parameters and determining which are inputs and which are outputs. The dataset then undergoes pre-processing steps before being divided into training, validation, and testing datasets. The modeling procedure begins by developing a basic model using shop test data (manufacturer data) to benchmark target parameters and determine whether a data-driven or hybrid model is necessary for engine condition monitoring. A neural network is then employed to capture data variance and leverage its ability to identify non-linear relationships. Building on the baseline neural network model, the loss function is customized to incorporate physics-based information into the data-driven model. This integration is achieved using two methods: either by approximating shop test data to represent engine behavior or by incorporating physical equations derived from mean value engine models. These physicsbased elements are introduced as new loss terms within the loss function evaluation. Each of the five developed model variations is then validated for their predictive capacity, with evaluation metrics compared to identify the most promising approach. Additionally, the models are assessed for their ability to generalize to unseen data. After concluding the modeling process, a case study was developed to examine the practical application of the best model in creating a condition monitoring tool. This tool relies on monitoring the residual trends of target parameters and correlating these trends with potential fault types in engine subsystems. By analyzing these residual trends, the model can effectively link subsystem degradation to overall engine underperformance, providing valuable insights for fault detection. Transitioning to the conclusions, it becomes clear that incorporating physics-based information, particularly from mean value models, yields superior results in capturing the variance of actual measurements and accurately predicting different operational conditions. This highlights the critical importance of developing hybrid approaches that combine the strengths of data-driven models while addressing their inconsistencies, thereby producing results closer to the ground truth. Further recommendations include integrating recurrent neural networks and establishing a decision support system to help identify the root causes of degradation and suggest necessary actions. Overall, developing a condition monitoring model proves beneficial for identifying underperformance and ensuring the correct operation of the vessel.

The demand for offshore marine contractor services is expected to increase in the coming years, whilst contractors, such as Boskalis, receive growing pressure to reduce greenhouse gas emissions from their offshore operations. Dynamic positioning (DP) is a crucial aspect of most offshore operations, but the high redundancy levels and frequent load variations present several problems and negatively impact fuel efficiency.

This MSc Thesis proposes improved diesel generator (DG) load allocation strategies as a method for reducing fuel consumption from DP operations of offshore vessels, considering existing ship designs and industry practices whilst maintaining high safety standards. The main principle of this solution is to improve the overall fuel consumption by allowing prime movers to operate at different loads. The main research objective of this report is to determine the fuel savings achieved through improved DG load allocation strategies for a selected case study, considering realistic operational constraints, standard industry practices, and a dynamic load profile which approximates real conditions.

A diving support vessel is selected as case study vessel based on its power system characteristics, operational profile, and expected load profile during DP operations. Realistic vessel limits and practices are gathered from operational vessel documents, and constraints are established for different load allocation strategies. Instead of using evolutionary algorithms to create DG sequences that are optimised for fuel efficiency, DG sequences are manually created and correspond to ten different load allocation strategies in order to maintain a clear structure which operators are able to utilise in real life.
The best DG sequences of each load allocation strategy are selected and further analysed in a preliminary analysis, providing the hourly fuel consumption of each load allocation strategy, between 0% and 110% MCR w.r.t. the benchmark strategy.
In addition, a dynamic model is developed to simulate a 24-hour DP operation of the selected case study vessel, providing information on the resulting fuel consumption and potential savings of different improved DG loading strategies for a dynamic load profile. This load profile changes over time to approximate real-life conditions, including most frequent power levels and occasional load transients.

Results indicated that all improved DG load allocation strategies provide fuel savings for both load cases w.r.t. the benchmark strategy. Savings are maximally 5.5% for open bus-tie configurations and 11.3% for closed bus-tie configurations.
Additionally, the outcomes of the dynamic model are compared to those provided by the preliminary analysis, which represents current state-of-the-art methods. The frequently low power levels and occasional load transients are not well represented by an operational average load, whilst these significantly influence the prospected fuel savings of the proposed solutions. Therefore, the results emphasise the importance of considering realistic industry practices and determining fuel consumption for a dynamic load profile which approximates real DP operations.

Although similar fuel savings are expected for other conventional diesel-electric DP vessels, the extent greatly depends on aspects such as the operational profile in DP mode or the fuel consumption characteristics of the power system. Actual fuel savings are likely lower as the effects of load transients are not widely considered within this research. Nevertheless, significant fuel savings are expected, as methods could be devised to limit this.
Ultimately, fuel savings from improved diesel generator load allocation strategies have been provided for realistic operational constraints, presenting an alternative out-of-the-box solution for reducing fuel consumption of Dynamic Positioning operations from Offshore Vessels.

De-carbonizing aviation is necessary for a sustainable future, and using hydrogen in a fuel cell, that produces water, can greatly reduce greenhouse gas emissions. Achieving higher gravimetric energy density with hydrogen compared to conventional jet fuels, involves storing it in cryogenic liquid form. Along with it, its cryogenic temperature range not only enables its use as chemical energy storage but also as a potential heat sink. However, rapid vaporization, known as boil-off, limits the long-term storage of liquid hydrogen in fuel tanks, requiring regular venting due to self-pressurization over time. Additionally, hydrogen needs to be heated to the fuel cell’s operating temperature before being used as a reactant. Understanding these requirements, this thesis focuses on three areas: predicting the maximum boil-off rate of liquid hydrogen while charging the fuel tank using a MATLAB simulation and the boil-off rate during the flight journey using a validated software called BoilFAST to understand the feasibility of retrieving the boil-off for its integration with the fuel supply; designing a fuel supply system that integrates the boil-off gas with the vaporized liquid hydrogen supply line to the fuel cell system; and integrating the cryogenic energy of hydrogen with a ram air-cooled vapor compression refrigeration system (VCRS) based thermal management of fuel cell, with the intention of reducing its parasitic load and improving system compactness. Two methods were used for the thermal integration: VCRS involving fuel cooled heat exchangers that function as an intercooler and as a separate de-superheater before a ram air-cooled condenser; and VCRS with a separate single-phase, 52\% ethylene-glycol based serial cooling circuit with multiple fuel cooled heat exchangers (FCHX). This resulted in a significant reduction of parasitic load by 13.4% and 26% when integrated with the intercooler system and single-phase serial cooling system, respectively. The study also examined the expected additional component weight, considering the aviation sector's preference for lighter systems. The findings demonstrate that the holding time of the fuel for minimum 13 minutes after tank filling and before the start of the propulsion system unit can allow a controlled amount of boil-off gas to be integrated with the fuel supply. Utilizing cryogenic energy for thermal management can significantly enhance the system's coefficient of performance by 15.3% and 33.3% respectively. Future work should involve experiments to obtain actual boil-off rates at different ambient exposures of fuel tank, tests on sloshing effect due to turbulence during flight journeys, analysis of thermal stress effects in cryogenic heat exchangers due to high temperature gradients, and testing new compatible mixed refrigerants with improved thermal properties for optimum cryogenic heat exchange.

The yachting industry is embracing sustainable practices in response to global environmental concerns, particularly those outlined in the Paris Agreement, which aim to reduce greenhouse gas emissions and limit global temperature increases. Although diesel engines are most commonly used in yachts and are a major contributor to greenhouse gas emissions, efforts are being made to minimise energy consumption through the use of alternative fuels. Auxiliary systems, such as heating, ventilation and air conditioning (HVAC), are also being studied for efficiency improvements. As yachts spend a considerable amount of time at anchor or in port, these systems account for a significant percentage of the total consumption.

This thesis focuses on estimating the energy demand of HVAC systems onboard yachts. In collaboration with De Voogt Naval Architects, part of Feadship, this research uses a grey box model approach, a combination of a white box and a black box, to estimate and evaluate HVAC systems. White box models are based on first principles or physics and are transparent models. This contrasts with black box models, which model a system based solely on observed data, without any prior knowledge of the system. These models are primarily machine learning algorithms such as artificial neural networks. Black box models perform better than white box models within the range of the trained data, but white box models excel at prediction outside this range. The integration of both models can combine the advantages of both into a grey box model.

The white box model described in this report is a type of predictive model that combines theoretical knowledge with empirical data to estimate the heat load for HVAC systems on yachts. The model uses theoretical principles derived from various methods, such as an ISO heat load balance, and incorporates empirical data collected from sensors installed on yachts, including temperature and humidity measurements. This data is used to simulate the performance of the HVAC system under different weather conditions.

The heat load estimation of the white box model is used as input for the greybox model combined with various sensor data. It makes use of a perceptron artificial neural network (ANN), that can learn from the data and adjust its predictions. The hyperparameters of the ANN are chosen and validated using a kfold cross validation. The final calculations are performed with the optimal configuration.

The results of the optimal model are validated against the power consumption recorded in the voyage data. The grey box model achieves a mean absolute percentage error (MAPE) accuracy of 91.3%, which is an improvement compared to the performance of the solo black box. Specifically, the MAPE accuracy of the grey box model is 0.9% higher along with similar improvements in other metrics.

Finally, the study provides an insight on the possible application of the grey box model. The solo white and black box models can also be used apart from the grey box model. A simple extrapolation analysis is conducted to provide insights on the capabilities of the model. With the implementation of these models, Feadship can predict the heat load and energy demand for varying weather conditions and ranges of data.

Hydrogen Polymer Electrolyte Membrane (PEM) fuel cell technology is becoming increasingly popular in the transportation sector, especially the automotive industry. It can power electric drives by converting hydrogen into electricity in a chemical reaction with oxygen, whose products consist only of water. Therefore, hydrogen PEM fuel cell-based powertrains are free of any harmful emissions, enabling clean propulsion technology. An important part of an automotive fuel cell system is the air processing subsystem, which usually features an electrical air compressor (E-compressor) to supply the necessary oxygen for the chemical reaction. This E-compressor can absorb between 10-30% of the fuel cell gross power. One way to decrease this share is to expand the fuel cell air exhaust flow in a turbine that contributes to power the E-compressor, essentially realizing an electric turbocharger (E-turbocharger). E-turbochargers for fuel cells are still in the development phase, therefore there is a lack of experience and knowledge on their benefit. In this thesis, a model of an existing automotive PEM fuel cell air processing system has been developed using the AVL Cruise M software. In addition, two prototype PEM fuel cell E-turbochargers (ETC1 and ETC2, respectively) have been modeled and integrated into the main air processing system model. Steady-state simulations have been performed for three different power levels. Moreover, the turbine inlet temperature of the ETC1-based model was varied in the range of 60°C to 150°C to quantify what benefits exhaust heating with waste heat brings in addition to the inherent turbocharging performance gains. The results show that compared to the baseline system, the model featuring ETC1 achieved an increase in net power between 3.04-6.78% or a decrease in fuel consumption between 3.19- 7.67%, depending on the power level. For the ETC2-based model, from low to high load, the net power increased between 1.88-2.04%, or fuel consumption decreased between 2.07-3.17% compared to the baseline system. When increasing the turbine inlet temperature to 150°C, the model showed an additional decrease in fuel consumption of 2.1 percentage points at full power. The models could be improved by implementing a first-principle-based model of the E-compressor and E-turbocharger, which could have been developed in this project if more detailed information on the heat flows within these components was available.

Reduction of carbon emissions and greenhouse gases within the transportation sector is crucial due to its significant contribution to environmental degradation. To reduce this impact, it is important to develop and implement energy efficient systems. In addition to exploring renewable fuel alternatives, effective energy management systems are vital. This paper presents an optimization-based control referred to as Hierarchical Model Predictive Control along with a comparative framework, to evaluate its effectiveness as a real-time control strategy. Three energy management strategies are designed for this purpose, with the objective of minimizing the fuel consumption of a hybrid marine powertrain, while optimizing the power distribution among its components to achieve high operational efficiency.

This master's thesis addresses the urgent need to reduce the marine industry's environmental impact. Van Oord, a marine player, aims to achieve carbon neutrality by 2050. The study investigates integrating methanol-fueled Solid Oxide Fuel Cells and batteries into the cable laying vessel NEXUS's power plant.

The research shows that integrating these technologies can offer acceptable operational capabilities and substantial greenhouse gas emissions reductions in the medium term. However, short-term implementation faces challenges due to current SOFC limitations.

Economically, long-term fuel cost savings make this integration viable, despite high initial capital expenditure.

The study includes a literature review favoring SOFCs and methanol for cable laying vessels. The case study proposes a 1926 kW SOFC and a 1195 kW battery pack integration, resulting in significant fuel consumption and emissions reductions while complying with regulations.

In conclusion, integrating methanol-fueled SOFCs and batteries in cable laying operations presents an opportunity for efficiency improvement and GHG reduction, with long-term economic benefits. This supports Van Oord's commitment to carbon neutrality and addresses the marine industry's environmental challenges

The increasing awareness and urgency of climate change have led to an increase in investments and research into power sources not reliant on fossil fuels. Proton exchange membrane (PEM) fuel cells are a promising technology for automotive, maritime, and auxiliary power applications converting chemical energy into electricity. In order for this upcoming technology to compete with well-established alternatives such as diesel generators and combustion engines, it is of vital importance to improve the power density and durability.

PEM fuel cells produce water and heat during operation. The presence of superfluous liquid water in the fuel cell stack gives rise to flooding of the electrodes, which hampers operation and induces degradation processes. On the other hand, it is of great importance to maintain a high membrane humidification to reduce Ohmic losses over the membranes and avoid the formation of cracks. Therefore, water management plays a vital role both in maintaining the power density and guaranteeing durability.

This thesis is written under the auspices of both TU Delft and PowerCell Group, a manufacturer of PEM fuel cell systems located in Gothenburg, Sweden. Currently, a substantial amount of water condenses in the anode subsystem of PowerCell’s PEM fuel cells in certain operating ranges which subsequently enters the fuel cell stack. This study identifies the influence of certain system operating parameters on responses as the water crossover through the membranes, the relative humidity at the stack inlet, the temperature at the inlet of the stack, the condensation rate in the mixing chamber of the recirculation loop, and the mass flow rates of liquid water and water vapor in and out of the stack. Multiphysics simulation software provided by Gamma technologies is used to simulate 5600 operating points in which the system operating parameters are varied according to the Latin Hypercube sampling method. These simulations give a clear overview of the influence of the operating parameters on the aforementioned responses over the entire operating range of PowerCell’s PS-100 system.

The simulated experiments are subsequently used as a basis to construct metamodels. These metamodels predict the behavior of the system based on the operating parameters varied in the 5600 simulations. The metamodels are constructed both as Krigings and as multilayer perceptrons (MLPs). Kriging is a statistical method which produces an output for a certain response based on known input data where input points which resemble the unknown point are given a greater weight. MLPs are neural networks which recognise patterns in input data and use those to predict an output for a certain response. Finally, the operating parameters are optimized using the metamodels to minimize the liquid water mass flow rate into the stack, to prevent condensation in the mixing chamber of the anode subsystem, and to target a certain inlet relative humidity of the hydrogen feed to the stack. Concluding from these optimizations it would be beneficial to preheat the hydrogen before it reaches the mixing chamber. A number of alternative designs for the anode loop are proposed which require further investigation.

The urgent need for marine transportation to reduce CO2 emissions has led to considering alternative energy and storage sources. The resulting increase in the complexity of powerplant architectures led to the development of advanced control strategies to achieve energy savings. At the same time, the health status of components has been often overlooked, leading to shortened powerplant lifecycles.

To address this issue, this paper proposes a novel health-aware control strategy for hybrid and full electric powerplants featuring fuel cells and batteries that simultaneously extend service life and reduce energy consumption. Specifically, the thesis identifies the most detrimental behaviour for powerplant components and propose a bespoke cost function to mitigate those.

To assess the effectiveness of the proposed control strategy, a comparative analysis will be conducted against a non-health-aware control strategie and a health aware control strategy from literature, to demonstrate the advantages of the proposed approach in terms of energy performance and service life extension, contributing to the development of sustainable marine transportation.

At the moment, Tata Steel emits 12.6 Mt CO2 per year while producing 7.2 Mt steel per year. To reduce these emissions, Tata Steel has decided to replace the blast furnaces with direct reduced iron (DRI) plants in combination with reducing electrical furnaces. The DRI plants will first operate with a 100% natural gas feed. Whenever green hydrogen becomes available on the market, the natural gas will gradually be substituted with green hydrogen, reducing direct CO2 emissions. Producing steel using 100% green hydrogen as the reducing gas, called green steel, comes along with an awkward problem regarding the carbon content of the DRI. Green steel has a carbon content of 0%, while carbon is essential for multiple aspects of the production process. Furthermore, the metallization of the DRI is a critical parameter in the production process. Thus, the following research question is established: ”What is the influence of the ratio of hydrogen to natural gas inserted in the direct reduced iron plant on the performance of the reactor?”

To answer this research question, an extensive literature review is performed to gain knowledge of the reduction process, reduction technologies, and the existing mathematical models of the DRI plant. Furthermore, a multiscale mathematical model is made of the shaft furnace of the MIDREX plant. This model uses a grain-based pellet model, which incorporates the morphological structure of the pellets during the reduction process. The shaft furnace is modelled as a 1D model with multiple zones, in which the local energy, mass, and momentum equations are solved. However, due to the time restrictions of the thesis period, only the two reduction zones of the shaft furnace are incorporated. Hence, the shaft furnace model lacks the transition and cooling zones.

The shaft furnace model is compared to a real operating MIDREX plant named ”Gilmore”. The simulation results are validated against the simulation results from literature and the real plant data. The average relative error of the simulation results compared to the Gilmore plant is 14.4%. The most significant error can be attributed to the carbon weight fraction in the solid. This is the result of the missing transition and cooling zones, as most of the carburization occurs inside the transition zone. Neglecting the carbon weight fraction, the average relative error is 9.2%.

Increasing the ratio H2 / CH4 in the feed of the MIDREX plant results in an increasing H2 / CO ratio of the reducing gas entering the shaft furnace. Five cases with different H2 / CO ratios are simulated to answer the research question. The metallization of the DRI is affected by two different phenomena. First, increasing the H2 / CO ratio results in a larger gas input mole flow for the same input pressure, which is the effect of a smaller pressure drop over the shaft furnace. Subsequently, a larger gas input mole flow results in better metallization, which is the effect of more heat input and a lower gas oxidation degree in the shaft furnace. Second, as the hydrogen content increases, the temperature decreases as a result of more endothermic reduction. The thermodynamics and kinetics of reduction by hydrogen are favourable at higher temperatures, which results in a slow-down of the reduction. At lower temperatures, the thermodynamics of reduction by carbon monoxide is more favourable, realizing more reduction and increasing the temperature. This second phenomenon is predominant for equal input mole flow, resulting in worse metallization when increasing the H2 / CO ratio, as confirmed by literature. Consequently, to achieve equal metallization for a higher H2 / CO ratio, the process gas compressors of the MIDREX plant will consume more electrical energy. To conclude, substituting natural gas with hydrogen does have its disadvantages, but it is highly necessary to become CO2 neutral in the future.

For further research, the addition of transition and cooling zones to the shaft furnace model is recommended, allowing investigation of the carburization of the DRI. Furthermore, the shaft furnace model is extremely useful for implementation in a complete MIDREX plant model. Such a model could be used to investigate the total CO2, energy, and material balance of the plant for different H2 / CH4 ratios of the feed of the plant.

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.

Internal combustion engine (ICE) emissions cause numerous social, environmental, health, and economic issues, including extreme weather or harm to public health. These effects are also experienced in the Chinese Pearl River Delta, where a high-speed, 200-passenger ferry named the Coastal Cruiser 200 (CC-200) uses ICEs to operate. The CC-200's designer, CoCo Yachts, is interested in the technical and economic feasibility of a zero-emission CC-200 variant to negate its contribution to the total ICE emissions. Investigating this interest is this study's purpose, as no currently-operating zero-emission ferries were identified that, at minimum, sail at 30 knots and carry 200 passengers. To reach the study's conclusions, primary and secondary quantitative data were collected, analyzed, and integrated into a parametric model developed to assess the ferry's technical feasibility. Moreover, this data were used to perform an economic assessment. Results showed that a 200-passenger, 30- to 40-knot, emission-free ferry is technically feasible and may or may not be economically feasible when implementing a battery-, compressed hydrogen-, or liquid hydrogen energy carrier system, hydrofoils, and all identified weight-saving measures. It was concluded that for these configurations, the 30-knot, battery-powered hydrofoil ferry has the highest likelihood of being both technically and economically feasible.

Shipping is, and will continue to be, the most important transportation method around the globe. A vital part of the logistic chain, it is also one of the main contributors to the worldwide CO2 emissions. Current propulsion technologies all rely on the same classic diesel driven technology, as diesel is widely available and has a high energy density.

The goal of this research is to identify greener solutions to propel a vessel sailing for short distances. During a definition study, several fuels and energy converters were studied and benchmarked based on a use case. The results showed that (a combination of) the dual fuel internal combustion, using bio diesel and hydrogen, and the low temperature proton exchange membrane fuel cell, fuelled with hydrogen, is the most feasible setup for the use case. Such a combination in itself is not a new one, but in the literature only an all-electric setup is described. In the proposed solution an internal combustion engine is driving the propellor shaft directly, assisted by an electric motor powered by the fuel cell.

Based on this outcome, the following research question was defined:

How can an internal combustion dual fuel engine and/or LTPEM fuel cell be integrated to form a cost effective solution to propel a short sea ship running on hydrogen?

First, nine designs were created, ranging from a conventional diesel engine setup as a reference case, to a fully electric design powered by fuel cells. All main components in these designs are analyzed regarding part load efficiencies. With these efficiencies, the fuel consumption at different loads are calculated. Based on a use case scenario the total fuel costs are calculated. The CAPEX and the OPEX of the designs are determined to calculate the total costs. As currently no other fuel can compete with diesel, the designs are compared based on the price per tons of CO2 emissions, as the shipping industry is expected to see a CO2 emission penalty in the near future. For each design, what the height of this penalty has to be to reach the breakeven point at the end of the use case was calculated. Based on the lowest CO2 price, an all-electric, fuel cell powered design was identified as the most promising option. Applying additional operational arguments such as redundancy and end user acceptance, it was decided together with Conoship to choose a combination of an internal combustion engine and a fuel cell.
This configuration is worked out in detail to answer the sub questions, covering efficiency improvement and system integration, during which it became apparent that not all information is available to answer all these sub questions. The design needs further research in a multidisciplinary team. A simulation model would be helpful in this further research. A framework and a start to such a model was written together with a list of recommendations.

This report will give an in depth view on the technical feasibility of placing an offshore platform from which watersports can be practiced in the waters surrounding the island of Bonaire. The feasibility research is done by appointment of two entrepreneurs on the island of Bonaire. The report will give an answer to the research question: Can an offshore floating platform, aimed at fast watersports, be built as sustainable as possible within the context of Bonaire? This research question can be divided into multiple sub-questions, being: 1. What is the context of Bonaire? 2. What is, for this report, the definition of sustainability? 3. What facilities are needed on the platform? 4. How can 100% renewable energy be generated for the platform? 5. What would such a (conceptual) platform look like? To answer these questions, the method as described in Kossiakoff (2011) is used. This method gives structure to the design of a system that has not been used before, but tries to combine older systems in new innovative ways. From this method, three important stages in the design process have been identified: The needs analyses, the concept exploration and the concept definition. This report follows that structure, starting with the chapter: Needs analyses. In this chapter, the report answers the first two sub-questions. The context of Bonaire can be described as: an island with opportunities for every-one, but the local environment suffers from the exponential growth of people and tourists that visit the island. For the second sub-question the definition of sustainability has been placed within this context of Bonaire, leading to a specialized definition of sustainability. This definition combined with the requirements of the clients has lead to a valid need for the platform. The concept exploration, gives options to answer those needs. It does so by researching a broad range of possible facilities for the platform. This broad research eventually leads to a morphological map from which 3 realistic and 1 futuristic concepts are designed. In the concept definition these 3 realistic concepts have been tested by an MCA resulting in one concept that has been worked out for various components, thus answering sub question 5. From this worked out concept, a conclusion is written in where the main conclusion is that an offshore platform aimed at fast water sports van be build sustainable within the context of Bonaire if the clients are able to make some consensus in there plans and the way they will use the platform. Finally, considering the sustainability of the proposed platform, it can be concluded with current technologies it is hard to build a platform without emissions, negative effects or any hidden impact. However, if the schedule and plans of the clients where to change towards a more ’nature dependent’ schedule (so taking peak energy generation into account). The platform could set an example and can even be a global ’first’ when it comes to making the practice of watersports more sustainable.

The issue of climate change has fostered the innovation of new technology in an attempt to curb the rising emissions, with the energy sector being one of the biggest contributors of carbon emissions. Renewable Energy has shown promise in reducing the emissions by up to 32 %. However the problem of intermittency of
renewable energy sources is still a big reason why they aren’t more mainstream. Therefore, hydrogen has been seen as an energy carrier to provide integration amongst the various sectors of energy generation, transportation, household heating and industrial use. The use of hydrogen as a fuel for re-electrification and power production can be done via IC engines, gas turbines and fuel cells.
This thesis is interested in the possible applications of re-electrification of hydrogen using a system consisting of an SOFC and a gas turbine. It aims to design a small lab scale, test-setup of such a power cycle. The setup
would consist of a small gas turbine and a solid oxide fuel cell.
To that end, this thesis introduces the importance of hydrogen as an energy storage medium followed by the advantages of the SOFC-GT systems in providing higher thermal efficiencies. This is followed by the introduction of the H2-O2 power cycles, namely the Graz and the Toshiba cycles. From previous research done at TU Delft, a basic schematic of the system has been shown, consisting of an SOFC, a combustor, and gas turbine, heat exchangers and an ejector for re-circulative cooling of the SOFC. This is the setup that has to be
designed and so the theory behind the components is presented.
Firstly, the theory behind solid oxide fuel cells, and their modelling is presented. The cooling of the SOFC has been looked into in greater detail. This is followed by the theory of combustion and turbulence modelling.
Two combustor types, a swirl based and a micromix have been considered. Out of these the micromix has been chosen because of its superior mixing capabilities. Finally, the theory behind ejectors, heat exchangers and
sizing of turbomachinery is presented. This concludes the theoretical background of the study. A 0-D model of the SOFC is made based on the Sunfire/Staxera Mk-200 ISM with the 3YSZ KeraCell 11 by Kerafol. This model is then used as a basis of design for the entire thermodynamic H2-O2 cycle. The designed thermodynamic cycle has an overall efficiency of 67.28 %. LHV of hydrogen.
The micromix combustor design is introduced next. A conceptual micromix geometry is presented following which, 2 different configurations are scaled and designed using the theory of jets in cross flow. The two configurations are compared after performing a CFD analysis using the k−ε model with equilibrium chemistry for combustion. The comparison is based on mixing performance, pressure drop and temperature contours. Following the design of the combustor, the supplementary components such as the heat exchangers and the
ejector are designed. The turbine is selected as a small radial turbocharger with a pressure ratio of 8 and is sized using the Balje diagrams. material recommendations are given for the combustor and high- temperature
heat exchangers. The final H2-O2 thermodynamic cycle is presented with the updated component designs. The final thermal efficiency is found to be 64.09 % LHV.
Finally, a basic control scheme is developed for the system and the start-up procedure is briefly discussed.

The reduction of the of harmful emissions that result fromyachting are an increasing concern and priority. It has been widely established that yachts have a significant contribution to the emission of greenhouse gasses and other emissions that are harmful to the environment and the public health. Measures must be taken that drastically reduce the environmental impact of yachts. The use of fuel cells, in combinations with alternative fuels, can provide a solution. The emission of all harmful emissions can be greatly reduced or completely eliminated. One of the major challenges in this transition is the uncertainty in the future supply of alternative fuels. Yachts are built to operate up-to 30 years, this is only possible if it is ensured of fuel supply over this time. Fuel-flexibility can provide a solution. If the operating fuel can be changed according to the availability, the yacht is guaranteed of operation in all future scenarios. This report describes research on how a fuelflexible fuel cell system can be designed that is capable op powering a super yacht. A selection of alternative fuels was made. These fuels must be suitable for marine application, they must hold environmental benefits over conventional fuels, and together they must ensure operation in all future scenarios. A number of fuels was considered. Their storage, production and feedstocks were compared. A final selection of operative fuels was made: it consists of ammonia, methanol, and bio/synthetic diesel. A fuel-flexible fuel cell system was designed based on the power demands of a yacht. The operational demands have been carefully mapped based on a yacht design of De Voogt Naval Architects. The system design is based on an SOFC with an external (pre-)reformer/cracking reactor. This reactor operates adiabatic and the required steam is supplied by water recirculation, both to increase the control over the fuel decomposition process. Waste heat is utilized in the balance of plant of the system, and can be recovered from the system in the form of a hot water flow. This heat can be consumed directly during the operation of the yacht. There are limitations in the fuel-flexibility of the system. Some of the components must be replaced when a switch between alternative fuels is made. A performance analysis is needed to find whether the fuel-flexible fuel cell system can power a yacht. A model of the system was made in which the performance of the system was simulated under the defined operational requirements. A thermodynamic analysis of the system is conducted to find the efficiencies and fuel consumption, and the heat and mass flows within the system. These parameters were used to calculate the yearly fuel consumption, emission of CO2, and required stored fuel capacity. The efficiency for the designed fuel-flexible fuel cell system is high for all of the fuels, and throughout the operation of the yacht. There is a large difference in fuel consumption and required fuel storage capacity between the alternative fuels, this is mainly caused by the energy density differences of the fuels. The emission of CO2 is depended on the fuel consumption and the carbon content of the fuels. Compared to conventional power generation and fossil fuels, the emission of CO2 is significantly reduced. There are also differences in the heat and mass flows within the system. Each fuel therefore has a different required capacity for pieces of equipment such as heat exchangers, pumps, and compressors. This research has shown how a fuel-flexible fuel cell system can be designed that is capable of powering a yacht. Through a thermodynamic model, it is shown that such a system has a high operational efficiency throughout the performance of the yacht. Harmful emissions are greatly reduced compared to conventional power generation. In a fuel-flexible system, each component must be designed for themost demanding fuel. For each fuel, some system components will therefore be over-dimensioned. A fuel-flexible system will be more complex and voluminous than a single-fuel fuel cell system. In return, the system will be operational in all future scenarios. This research has shed light on the trade-offs that the choice for a fuel-flexible fuel cell system can bring about. It provides an analysis which will only become more valuable as the yachting industry is urged to adapt to an ever-changing environment

The current path the marine industry is following, the goals of the Paris Agreement to reduce emissions, will not be met. The marine industry is mainly sailing on HFO and emits 2.2% of the global greenhouse gasses (GHG) by doing so, as well as 18-30% of NOx, 5-8% SOx and 11% particulate matter (PM). The IMO has even predicted that the emissions of GHG will increase between 50 and 250% if the shipping industry continues on this path. In order to reduce emissions, the International Maritime Organization (IMO) has implemented ambitious goals for the next decades. However, the current policy measures sparks low ambition to meet this IMO GHG strategy. To be able to meet this goals, four options with different potential of reducing emissions are available, viz. efficient ship hull designs (20%), energy efficient engines (10-15%), more efficient propulsion (5-20%), clean technologies such as fuel cells and the use of alternative fuels (100%). Since the alternative fuel option has the largest potential in reducing emissions, a number of researched have looked into possible options for alternative fuel, such as LNG, LPG, methanol, biofuel, hydrogen and ammonia. This thesis looks into the potential of ammonia as an alternative fuel in the marine sector by 2030 by looking into the critical success factor for the fuel.
This research takes all the aspects of the marine industry into account and researches the mutual interaction and relation between the aspects. The main aspects are the power generation options, the fuel availability including the port logistics, price of the fuel, operations (OPEX), impact on the vessel (CAPEX) and legislation and rules. These aspects have a number of inter-dependencies.
The barrier related to the power generation option is the lack of availability of an engine that can run on ammonia. This engine needs to comply with legislation, which is not implemented yet. The barrier related to the fuel itself is the availability of the fuel in both volume and location. The production capacity is not yet at a level to fuel a significant part of the marine sector. The barrier related to the port are the logistics of the supplier and storage and handling of ammonia. Ammonia is a toxic substance and requires safety measures. These rules have not been implemented either. Closely related to the availability of the fuel is the price of the fuel. This is dependent on the demand of ammonia, which is currently zero for the marine sector. For the operational aspect is the lower energy density compared to conventional fuel an important barrier. For the same energy output, a greater volume of fuel is needed. This requires either extra stop overs during the voyage or a larger fuel tank, which could lead to loss of cargo space. The larger fuel tank has an impact on the design of the vessel, as well as the different storage and handling of ammonia compared to conventional fuels. Together with the legislation, this is an important barrier for the CAPEX of the vessel. This is a very important decision factor for the ship owner. Finally, most important barriers is the legislation. This aspect has the largest influence on all the other aspect and can promote other aspects to invest in ammonia and take steps in implementation. The regulation for sailing on ammonia are not yet in place. The IMO is responsible for the IGC and IGF code that regulate fluids as cargo and as fuel. The IMO has not started working on implementing ammonia as a fuel yet, since the demand of the fuel is currently low. This is however due to the regulations not yet being in place. Ship owners are reluctant to switch to another fuel when the risk of implementing the rules incorrectly are too large. The design requirements are not yet clear and it would be too costly to refit a vessel to the correct requirements for the early adaptors. Another aspect the regulations have large impact on are the engine options. Ammonia has a narrow flammability and is more difficult to ignite compared to conventional fuels. The design of the engine needs to comply with the regulations for safe ignition.