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.

In recent years, the demand for renewable energy has increased significantly because of its lower environmental impact than conventional energy technologies. As a result, wind power is one of the most important renewable energy sources. As land-based turbines have reached their maximum potential, recent market trends are moving into deeper waters with higher capacity turbines. The design of a floating offshore wind turbine (FOWT) foundation poses technical challenges. Mooring design, installation operations and the fact that it is a new engineering field, to name a few. Moreover, as mooring design for FOWT is still at an early stage of development, cost-effective installation remains one of the critical issues. After the FOWT is towed to the site, the mooring lines are hooked up, and one line is usually shortened. This can be performed in three ways: By seabed tensioning, inline tensioning or tensioning at the fairlead. In this investigation, details about mooring installation processes are collected from interviews, academic papers, manuals and videos to investigate differences between mooring system installations and ultimately figure out how pre-tensioning of these systems can be carried out most effectively. This work presents a comparison between these three existing methods for the final phase of mooring installation. To perform a quantitative study, the Umaine VolturnUS-S 15MW floater is considered. Current modelling techniques are expanded to allow for the static simulation of the rotations or sliding at the tensioning device. The model framework is used to find the static equilibrium and tensions at different phases in the installation operations. Additionally, an alternative mooring configuration is proposed with synthetic inserts to verify whether the tension is dependent on the mooring configuration. Finally, the dynamics between the anchor handling vessel(AHV), the FOWT and the mooring chains are modelled as a linear mass-spring system. Vessel responses and work wire tensions are compared against each other for identical environmental conditions and equipment specifications. Based on simulation results, it is found that the seabed tensioner causes little dynamic relation between the AHV and the floater and was not further investigated. Inline tensioning showed to be the method that requires the lowest tensions in the AHV work wire. Fairlead tensioning was found to be discouraged since the high required bollard pull forces. This issue is mitigated by a proposed new concept of fairlead tensioning. When the chain is hauled in from above the fairlead by a vessel crane or A-frame, it is possible to tension effectively without fuel-intense bollard pull.

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.

In recent years, there has been growing interest in exploring the deployment of wave energy converters (WECs) in remote and harsh environments. However, research in this area remains limited, particularly concerning offshore environments with sea ice. This study focuses on investigating the energy production and economic feasibility of a point absorber in the Baltic Sea, specifically off the coast of Åland, which experiences seasonal ice cover. Four winter seasons with varying ice conditions are examined, ranging from ice-free to severe ice conditions. Additionally, the study aims to assess the survivability of the WEC under extreme level ice action and extreme wave conditions. Based on literature review, a hexagonal slope-shaped buoy has shown promise in withstanding ice conditions up to 15 cm thickness in the Baltic Sea and is selected as the WEC design in this study. Metocean and sea ice data spanning from 2006 to 2021 are analysed from the NORA3 database. Through extreme value analysis, key parameters such as wave height, period, and ice thickness are determined. Survivability analysis is conducted to understand the forces exerted on the WEC during extreme ice load cases and extreme sea states. To evaluate energy production, hydrodynamic coefficients are computed using the Boundary Element Method solver Capytaine in the frequency domain. Subsequently, simulations are conducted using WEC-Sim to derive the power output of the WEC under varying sea states. Optimisation of the Power Take-Off (PTO) damping is performed to enhance performance for the specific site conditions. A comparison of power output is made among different WEC configurations with varying translator sizes. The survivability analysis reveals important design considerations, especially regarding extreme ice conditions. When subjected to an extreme level ice thickness of 60 cm this results in calculated horizontal and vertical forces of 615 kN and 315 kN, respectively. In extreme sea states, simulations in WEC-Sim shows a maximum heave response of 4.16 m and a maximum heave force of 133 kN. Additionally, the investigation reveals significant fluctuations in wave energy converter (WEC) power production across the analysed winter seasons, characterised by varying ice conditions. During severe ice conditions (2009-2010), energy output decreased by nearly 50% compared to ice-free periods (2019-2020), potentially leading to a 95% increase in the levelised cost of energy (LCOE) if solely derived from that single season. These findings give valuable insights into the optimal WEC configuration, the maximising of power output and offer important considerations to WEC survivability for deployment in ice-covered regions.

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.

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.