This thesis dives into the collision dynamics between an ice ridge and a moored point absorber-type wave energy converter. The collision dynamics in this case encompass the ice–structure interaction forces, the resulting mooring line tensions, and the point absorber’s behaviour after impact.

For this research a 3D-model was developed using DualSPHysics, complemented by MoorDyn for mooring line dynamics and Project Chrono for collision dynamics. This research examined collisions between ice ridges modelled as rigid structures with typical subarctic dimensions and a moored buoy representing the point absorber. Various simulations were run with variations in ice ridge size, surface roughness of the ice ridge and different failure mechanisms for the mooring lines.

Key findings indicated that mooring line failures at a tension limit of 5 MN predominantly resulted from entanglement with rough keel surfaces rather than direct impact forces alone when ice crushing was neglected. Smooth-surfaced ridges allowed mooring lines to withstand tensions up to approximately 2.2 MN. Additionally, reducing ridge dimensions significantly decreased maximum tensions and horizontal contact forces, highlighting the critical role of ridge size and surface roughness in collision dynamics.

From this study it becomes clear that the highest uncertainty lies within ice crushing during the interaction with the ice ridge keel structure, it is expected to happen when the point absorber slides against the ice ridge, which can lead to entanglement of the point absorber within the ridge itself. This study contributes critical insights and provides a computational SPH-model for preliminary testing and analysis of moored point absorbers under ice ridge collision scenarios.

The transition to a low carbon energy system is focusing attention on the synergies between large scale offshore wind and green hydrogen production. These synergies can have system-wide benefits for the integration of wind farms to the power system, whilst improving their economic performance. Offshore wind investments face multiple uncertainties: commodity prices fluctuate and impact turbine cost, vessel rates required to install the turbines are dynamic and the electricity price fluctuates daily. Additionally, to realize wind-hydrogen synergies (hybrid powerplants) the electrolyzer is an additional source of cost uncertainty. On the contrary, the revenue uncertainty of the wind farm is expected to be mitigated through the use of Hydrogen Purchase Agreements. To take informed investment decisions regarding wind-hydrogen synergies, Vattenfall, a leading European utility, is interested in analyzing the trade-off between increased cost uncertainty and reduced revenue uncertainty.

This thesis investigates how integrating a 400 MW onshore electrolyzer with a 2 GW bottom-fixed wind farm affects the project’s economic uncertainty. To answer the question, a three-step methodology is applied. Firstly, the economics of the offshore wind farm and hybrid powerplant are modelled without the presence of uncertainty, using Vattenfall’s techno-economic model. This model considers investment and operation costs, along with the revenues of the wind farm from electricity sales on the power market. For the revenues of the hybrid powerplant, an optimization algorithm deciding when it is optimal to produce hydrogen or electricity is employed. Secondly, the uncertainties in key commodities (steel, aluminum, copper and shipping fuel oil), vessel day-rates, electricity prices and electrolyzer costs, are defined. Thirdly, the uncertainties are sampled through a Monte Carlo simulation to create 10,000 different realizations of the project, covering the entire range of possible outcomes. By combining the techno-economic model, the dispatch algorithm and the Monte Carlo approach, the uncertainties of the offshore farm and hybrid powerplant can be quantified, and their impact on the project economics can be evaluated.

The methodology allows to compare the effect of hydrogen integration in the business case uncertainty of an offshore wind farm. On a deterministic comparison, the two projects perform similarly. For the considered wind farm, the inclusion of the electrolyzer adds an additional e94 M
in cost uncertainty, while it reduces revenue uncertainty by e18 M. These results hold true for the considered offshore farm, given projected conditions and modelling assumptions. For this case, the offshore wind farm is marginally more certain in terms of economic returns. Given the two projects produce similar investment returns, accepting the increased uncertainty of the hybrid powerplant is non-economical.

The results of the thesis do not favor an investment in hybrid project in terms of uncertainties. However, this result is true for the project investigated and as conditions change and hydrogen technology matures, the analysis can shift in favor of hydrogen. Specifically, hydrogen is a large
scale infrastructure with the first full scale projects currently under development. With more project-experience gained, the uncertainty in costs can be reduced, favoring the hybrid projects. With increased support for large scale hydrogen production, the proposed framework for continuous analysis can be leveraged to keep pace with the external macroeconomic changes. The methodology can be extended and applied to other hybrid solutions, such as hybrid projects with batteries.

The global energy landscape is undergoing a significant transformation, marked by the increasing fragility of conventional energy systems and a decisive shift towards electrification to meet climate objectives. This transition elevates energy security and resilience to core priorities for governments and industries. Offshore artificial energy islands are emerging as pivotal strategic infrastructures, particularly in regions like the North Sea, designed to expand renewable energy capacity, alleviate grid congestion, and facilitate power exchange, thereby supporting overarching climate and energy security goals. This thesis investigates how integrating multiple functionalities, specifically energy generation and port logistics, within a single offshore island could enhance financial feasibility. The central research problem addresses how to assess the techno-economic viability of such multi-functional offshore islands, with the Princess Elisabeth Island (PEI) in the Belgian North Sea serving as a representative case study. Current assessment methodologies often fall short in comprehensively evaluating the intertwined financial and operational aspects of combining distinct energy and port functionalities on a unified offshore platform, creating a notable research gap. The primary objective of this research is, therefore, to develop and apply a standardized, transparent Techno-Economic Analysis (TEA) framework tailored for these complex, integrated systems.

The methodological approach is rooted in a TEA framework, systematically applied to the PEI case. This involves a physical breakdown of systems, detailed financial analysis including CAPEX, OPEX, revenue projections, and cash flow modeling, and performance analysis using key metrics such as Levelized Cost of Energy (LCOE), Net Present Value (NPV), and payback periods. The PEI project, planned for 3.5 GW of offshore wind connected via an artificial island housing AC and HVDC substations, formed the initial focus. The base case analysis for PEI as a standalone wind energy hub revealed significant financial challenges: amedian LCOE of 224 =C/MWh, substantially exceeding recent offshore wind strike prices, and a consistently negative NPV. This financial vulnerability is largely attributed to the dramatic increase in transmission infrastructure costs, which now account for nearly 50% of the total project CAPEX, a sharp rise from approximately 18% in 2020. Sensitivity analyses indicated that the LCOE is highly susceptible to project delays, ranging from 200 to 260 =C/MWh, and noted a cooling investor appetite in the European offshore wind sector. Enhanced base case considerations for the wind system showed that an AC-only configuration could reduce the LCOE to 182 =C/MWh, while incorporating HVDC as an interconnector, despite potential arbitrage revenues, increased the LCOE to 237 =C/MWh, illustrating a trade-off between strategic energy security benefits and immediate financial viability...

Floating offshore wind farms enable wind energy deployment in deeper waters, where bottom-fixed turbines are not viable. However, integrating mooring systems and dynamic cables introduces additional challenges in cable routing, increasing design constraints and costs. While research on cable optimization for bottom-fixed wind farms is well-developed, studies focused on floating wind farms remain limited.
This thesis presents an optimization framework that minimizes inter-array cable length while ensuring compliance with mooring system constraints and loop topology requirements. A Mixed-Integer Linear Programming model is used to enforce spatial and technical constraints, structured into three phases: preprocessing, optimization, and postprocessing. Preprocessing defines feasible cable connections while preventing crossings with mooring lines. To manage complexity, turbines are grouped into clusters with defined boundaries to separate routing areas. The optimization phase determines the best cable layout while ensuring loop connectivity and balanced electrical loads. Postprocessing checks compliance with industry standards, identifying clearance violations and refining layouts for feasibility.
A case study of the London Array wind farm demonstrates the model’s effectiveness, achieving a 1.1% reduction in total cable length while maintaining the original layout structure. When adapted for floating wind, spatial constraints from mooring systems cause clearance conflicts, which are mostly resolved by scaling the layout. Minor turbine adjustments eliminate remaining issues. The study highlights that increasing the number of loops and reducing loop size creates more routing conflicts, particularly near the offshore substation and at cluster boundaries. It also finds that centrally positioned substations significantly reduce clearance violations compared to those at the field boundary.
This research provides practical insights into the spatial constraints of floating wind farms and offers a structured, computationally feasible approach to optimizing inter-array cable routing for large-scale farms.

Harnessing wave energy from the world’s oceans provides an enormous chance to fulfil substantial parts of the energy transition’s demand for electricity from renewable sources. The technology that makes this possible is wave energy converters (WECs) - offshore structures that can convert the energy in waves into electricity. Although the energy conversion of this precommercial technology is not directly linked to greenhouse gas emissions like in other conventional power plants, environmental sustainability over the whole life cycle of the device needs to be ensured for a sustainable large-scale application. To assess this, in recent decades some Life Cycle Assessment (LCA) studies have been carried out on different WECs. However, there is still a gap in terms of number, quality, coverage of more sustainable design alternatives as well as impact assessment beyond greenhouse gas (GHG) emissions. Therefore, in this study a specific type of WEC – the point absorber – is assessed for its environmental sustainability by means of LCA. A parameterized cradle-to-grave LCA model of a single representative point absorber is implemented to assess the environmental impacts of a WEC, the influence of different hull materials, hotspots in impacts of WEC components as well as variations induced by different deployment locations. A GHG-intensity of 300-325gCO2eq./kWh with periphery and 52-77gCO2eq./kWh without periphery is found for a WEC deployed in the Dutch North Sea depending on the hull material. Using an alternative fibre reinforced concrete material for the hull can reduce impacts across all impact categories between 10% and 78%. Next to the structural materials in the WEC the electrical cable and vessel operations, especially for maintenance, were found to contribute significantly. This study showed that impacts of electricity from WECs have to decrease to reach the level of other renewable electricity generation technologies but revealed possible levers to achieve such a reduction.

To stay on track for the 1.5°C pathway of the Paris Agreement, an accelerated energy transition is essential. Efficient offshore energy infrastructure planning, incorporating novel methods, is crucial and requires transparent, industry-wide discussion. However, two main challenges emerge: (i) the often-overlooked integration of energy islands in literature and (ii) the lack of a standardized techno-economic comparison method. A comprehensive review of offshore wind supply chain feasibility studies highlighted the need for explicit implementation of standardization, syntax and semantics in model development. Detailed assessment of international and industry standards revealed that no single standard fully covers the study's scope. Nevertheless, one ISO standard showed significant similarities in component definitions, with which this study's component definition is maximally aligned. The developed open-source model enables automated supply chain configuration generation, eventually calculating economic metrics such as the Levelized Cost of Hydrogen (LCOH). Applying the developed techno-economic model to the 19.5GW case study hub North in the North Sea Energy programme demonstrated its applicability and the techno-economic advantages of integrating an offshore energy island. The key finding is that island-based configurations are economically more efficient for hydrogen production compared to platform or onshore setups. Comparison with other studies on hydrogen import indicates that the calculated LCOH range of 8.54 - 10.40 €/kg has the potential to compete with hydrogen imports, which often have overly optimistic estimates ranging from 4 to 9 €/kg. Ultimately, in this way, a standardized, transparent method for industry-wide collaboration is presented.

The offshore wind market has become a substantially growing industry to meet the worldwide increasing energy demands. This results in heavier crane operations on offshore jack-up vessels due to the increasing size of wind turbine components. To ensure the seabed can support the loads on the jack-up legs, a temporary foundation for the leg's footings is established before crane operations through a process known as preloading. Where the two diagonal opposing leg pairs are loaded alternatively by the weight of the vessel until a stable condition is reached. Traditionally, the capacity of those foundations is determined based on storm loads adopted from offshore oil and gas jack-up guidelines.

The main objective of this thesis is to develop a robust method for analysing the applied preload in past jack-up crane operations conducted by Jan de Nul's Vole au vent. This analysis aims to provide a better understanding of the effectiveness of traditional offshore jack-up guidelines within the rapidly growing offshore wind industry, where heavy crane operations are now performed on a daily basis. Such understanding is crucial, as these guidelines were not originally intended for the advanced state of the current offshore wind sector and are not specifically calibrated for its unique demands.

To accomplish this objective, a method is designed to assess the preload safety factors of past jacking operations and determine their optimal value for heavy lifting operations. This safety factor provides the ratio between operational leg reactions and applied preload. The developed models are then applied to a case study using measuring data from jacking operations of the Vole au vent to validate their effectiveness.

This method is based on reliability analyses which evaluate the probability of failure by assessing if a certain limit state is exceeded. Failure for jacking operations can occur when the leg reactions during crane operations become larger than the applied preload. From the acquired measuring data, certain probability distributions of the leg reactions can be obtained, which are used by a Monte Carlo Simulation to assess the probability of preload exceedance through the defined limit states. This probability of preload exceedance quantifies the reliability of the applied preload in different soil types at three offshore wind farm sites.

This research then defines optimal targets for the annual probability of preload exceedance based on the consequences of failure of operations in both low-risk and high-risk soil profiles. These targets provide a balance between operational efficiency and safety. From those targets, an optimal preload safety factor is obtained and compared to what was originally applied during the jack-up operations.

The findings of this thesis indicate the need to evaluate and improve the standards to better align with the industry's evolving requirements.

It is shown that the currently used preload safety factor from traditional offshore jack-up guidelines is not yet correctly calibrated for heavy crane operations on jack-up vessels. To achieve an optimal balance between operational efficiency and safety, the applied preload, with respect to the experienced loads from heavy crane operations, should be slightly lowered compared to what is currently applied.

In addition, this research observed that the measured conditions during jack-up operations are not correctly estimated, leading to operational and preload uncertainties.

The rapid growth of Floating Offshore Wind (FOW) has spurred intensive research across various aspects of the floating system. A standard practice in mooring system design within the industry is that anchors remain fixed on the seabed. In contrast, plate-type anchors exhibit mobility under loading, a crucial factor considering the thousands of loading cycles experienced by FOW turbines during operation. Understanding the strain accumulation mechanism during cyclic loading has substantial implications for design. This thesis delves into the behavior of Drag Embedded Anchors (DEAs) subjected to static monotonic and cyclic loading, utilizing 3-dimensional Finite Element simulations. The installation trajectory of DEAs is initially defined through established analytical methodologies. Subsequently, the movement of the anchor and soil response under monotonic and cyclic loads is elucidated. Analytical expressions for monotonic force-displacement curves are examined, identifying optimal models and offering relevant parameter values for different anchor trajectory points. Under cyclic loading, the influence of average load and cyclic load amplitude is studied, along with exploring the feasibility of applying an existing 1-dimensional model for predicting anchor response.

During single-blade offshore wind turbine (OWT) installation, wind disturbance results in blade root motion. The sensitivity to this wind disturbance is more significant for larger blades, reducing the allowable installation weather limit. A potential solution is a Hook Mounted Compensator (HMC) between the crane and the load that can provide high-precision compensation across multiple degree of freedom (DOF), and compensate for the influence of wind on the OWT blade. Several Actuation Method (AM)s have been identified that can be used in a HMC. However, these AMs have not been modelled dynamically and their effectiveness for the desired application is unknown. The aim of this study is to analyse and assess the compensation effectiveness of these AMs in a HMC. For this purpose, the AMs are simulated and analysed in various levels of complexity and DOFs. Initially, the system is considered in a 1DOF. A linear representation is formulated, based on which a Proportional-Integral-Derivative (PID) controller for each AM is formulated. This enables simulation of the Single-Blade Installation System (SBIS) in the time domain. Assessment criteria are used to quantify the compensation effectiveness and actuation input of the AMs. To simulate the SBIS for each AM, 3DOF numerical models are developed that describe the operation of the AMs in their respective operational planes. Six actuation methods are included in the assessment. Based on the assessment results, three AMs are combined in a HMC concept. A XY table is used to control blade root position in the x- and y-directions, gyroscopes for the z-direction, and COG shifting with counterweight to prevent gyroscope saturation. The PID controllers based on the linear 1DOF representation are used, operating in parallel, to control the blade root position in all DOF. The blade root motion is reduced by 96% along the blade axis and 86% radially. The blade root motion is sensitive to the mean wind speed, turbulence intensity, and angle of the incoming wind. The HMC shows robustness to variations in tugger line angle and pretension. The static blade pitch angle affects the magnitude and distribution of the wind-induced moment on the blade. For a pitch angle of -180, the moment around the z-axis is minimal, providing optimal HMC performance. The HMC concept can not directly actuate the blade around the z-axis. Instead, the XY table translates the blade at the COG, resulting in increased cylinder stroke and high power consumption for other pitch angles. Two AMs were assessed to actuate the blade around the z-axis, both showing poor performance. Further exploration of AMS that can directly control the blade rotation around the z-axis could lead to improvement of the HMC concept. Additional improvement can be made in optimization of counterweight and gyroscopes sizes, potentially reducing weight and improving system performance. Further suggestions for future work include; exploring the compensating for the now neglected hub motion using the HMC, examining the stability of the HMC once the blade is mated to the hub, and the impact of sensor noise and delay on the HMC’s performance.

To facilitate the energy transition, effective collaboration among all stakeholders is necessary. However, there is currently a lack of understanding regarding the impact of different components in the value chain on the energy system's overall structure and the final energy price. This knowledge gap poses a significant obstacle to cooperation and progress in the energy transition. It creates the risk that effort goes into developing certain partial solutions when they may not be feasible from a larger system perspective. By focusing on their own component, stakeholders do not fully take into account the needs and interests of others involved. As the development of green hydrogen projects is in its early stages, it is important to think in terms of systems. Stakeholders should establish an ecosystem where players operating in different parts of the value chain are collaborating together. This helps to de-risk projects, share lessons and promote the development of innovative, first-mover initiatives.

This study aims to develop a standardised method to evaluate offshore wind to hydrogen concepts through a techno-economic analysis. This analysis method combines technical analysis with economic evaluation of projects and concepts to determine the potential economic outcomes and impacts of implementing a particular technology or project.

Through stakeholder interviews, the study found that stakeholders in the offshore wind and hydrogen market have distinct objectives and concerns. Key factors influencing their willingness to contribute include confidentiality, competition, and reputation.

To increase the transparency of the model, it was developed in Python. A standard notation system was developed, which was presented alongside the model's results. This should aid in the understanding of the underlying assumptions.

This research aims to improve the current knowledge and insight into the construction process, logistics, and construction costs associated with the offshore pumped storage hydropower plant. The main objective is to enhance the construction costs by optimizing the work method based on these sheltering effects.

The diffraction and sheltering effects due to the caisson dam will be determined using the Goda diffraction tables. Additionally, the Levelised Cost of Storage (LCOS) will be used to assess the cost-effectiveness of this bulk energy storage technology and enables the comparison with alternatives, such as lithium-ion and hydrogen storage.

In summary, this research addresses the promising potentials of work method optimization for offshore caisson projects regarding the local wave climate. For a case study in the North Sea, it has not only highlighted the relevance and importance of including wave sheltering. Moreover, with a LCOS of € 140-260/MWh it also shows the competitiveness of the offshore pumped storage hydropower concept once again. Alternative energy storage methods such as lithium-ion or hydrogen are in the range of € 200-400/MWh for lithium-ion and € 200-1900/MWh for hydrogen storage. Therefore, offshore pumped storage hydropower (PSH) can be a favorable solution enhancing the energy transition.

The purpose of this report is to design a wave energy converter, in particular a U-oscillating water column (U-OWC), to maximize energy conversion in the low wave energy environment of Gwadar, Pakistan. At present Pakistan’s 1000km coastline is largely undeveloped and the county is devoid of any wave energy harnessing devices or studies. However, recent years have seen an influx of Chinese investment being made under the China-Pakistan economic corridor agreement, which is stimulus for the near future construction of a large rubble mound breakwater to shelter an assistance vessel basin in the city of Gwadar.

Typically, a WEC is not feasible in low incident wave energy environments because the economic return from minimal energy generation cannot offset the capital cost of the structure. However, the opportunity in Gwadar is unique in the sense that a substantial investment is already envisaged for the creation of a breakwater. Therefore, it is worth investigating if re-designing this structure with vertical caissons embedded with U-OWC chambers is feasible. In this way, the structure can fulfill the dual role of sheltering the assistance vessel basin against wave attack, and produce renewable energy over its design life.

To assist with this task, existing data and methods available in literature along with numerical codes have been utilized. A 10 year SWAN hindcast has been performed, the result of which have been condensed into 60 representative design sea-states on the basis of which the U-OWC chamber geometry
and turbine configuration have been optimized. This was achieved by employing a random sampling technique to determine which combinations produce the most power and by identifying the ideal turbine
operating revolutions for each sea-state.

Next, the approximate cost of the caisson breakwater integrated with U-OWC chambers is calculated and compared against the currently proposed rubble mound design. It is expected that despite an attempt to maximize the energy generation by the device, its levelized cost of energy will be high, given
the low wave energy in the region. Nevertheless, if the design proves cheaper than its rubble mound counterpart, it goes to show that wave energy converter can be deployed in low energy environments provided an opportunity exists where they can be integrated into proposed marine structures. This will
be an important finding, considering that the majority of the global coastline is subjected to moderate to low incident wave energy, and neglected from WEC deployment considerations.