Auction systems have been around for a long time now, and they are proving to be a good support instrument to promote renewable energy technologies in most parts of the world. The key feature of an auction is its design flexibility, real price discovery through competition, transparency and greater certainty for investors and policymakers to achieve high-level targets.  This thesis uses specific design elements and assessment criteria for auction systems, set out in the literature, to perform a comparative analysis of the design elements of offshore wind auctions in the UK and the Netherlands to identify best practices in auctions that promote the development of offshore wind and provide recommendations to policymakers based on previous experiences in both countries.  The analyses show that strict selection criteria and penalties help improve effectiveness and static efficiency. Seal-bid auctions with multiple rounds and fixed schedules help to reduce uncertainty for investors. Financial prequalification in the form of seabed leases ensures that developers are serious about the project and improves realization rates. Physical prequalification should be set focusing on improving the supply chain in the region, socio-political feasibility, actor diversity, etc. However, it is advisable to exclude the EIA and grid connection from the scope of the developer as it helps reduce planning risks. It is important to have ceiling prices in offshore wind auctions, but a detailed study of the technological development and market condition needs to be assessed to set the right value and have it undisclosed for better competition. Separate budgets can be set for offshore wind auctions rather than have it based on capacity or electricity generation. This helps with better planning for the auctions. Support mechanisms should be designed to ensure that generators and consumers are benefited from them. Finally, a realization period should be set for projects to ensure they are aligned with national policy targets.

Background: This research work takes a strong sustainability approach with the focus on renewable energy technology (RET) diffusion to meet the multifold and complex challenges with CO2 emission targets and geopolitical energy challenges. Global warming, sustainability issues and significant energy crises, suggests that RET is seen as one of the most important solutions to deal with these challenges. Wind energy has been identified to have a leading role in achieving a low-carbon or completely carbon-free energy sector. Sweden is in the forefront of an energy transition having ambitious goals, and the lack of renewable energy sources may potentially become a problem. Diffusion of new technology may facilitate access to new resources at non-exploited areas, why the challenges to implementation of Floating Offshore Wind Technology (FOWT) and how the technology will diffuse in Sweden is the focus of this research study. Objectives: The purpose and aim of this study is to establish an understanding of diffusion and its drivers and challenges related to FOWT in Sweden and contribute with new knowledge in the field of renewable energy sources. FOWT may facilitate access to new wind resources at deep water conditions, why this study research the challenges to implementation of FOWT and how the technology will diffuse in Sweden. Methodology: The research area is limited to Sweden where main drivers and challenges are identified and framed by literature review of Porter’s Diamond model competitiveness factors and interviewing experts within the Offshore Wind Energy (OWE) industry. The qualitative interview results are applied in the Technology Acceptance Model (TAM) framework, where Innovation Diffusion Technology (IDT) model is used as theoretical framework to build up an understanding of the level of FOWT diffusion in Sweden and how it will diffuse. We use the concept of TAM in combination with IDT to explain how FOWT as a new technology is perceived to be used in the OWE industry with a particular focus on the challenges related to the implementation of FOWT in Sweden. Results: We provide guidance for the OWE industry stakeholders and valuable information of what need to be in focus to resolve challenges for implementation, and the diffusion of FOWT in Sweden. Our general assessment show that the market is positive about the technology. On the other hand, we find that the challenges are multifold and further complicates the implementation phase. Although FOWT has support from climate and environmental impact, the technology has limitations that can negatively affect the Behavioral Intention to Use (BIU). Conclusions: The challenges to implementing FOWT are multifold and concluded to be high risk premium for investors with limited scale effects due to substantiated grids and infrastructure. Collaboration issues between investors and government agencies are obvious, this in terms of inefficient permit processes and general understanding of the impact of the technology for decision-makers within the FOWT value chain. The interview results and IDT analysis direct that FOWT is in the stage of persuasion and will from this stage progress further to the decision and implementation phase of diffusion. Our arguments are based on the identified level of knowledge maturity present among the interviewed stakeholders, and the fact that policy and specialist reports include FOWT when evaluating RET alternatives for new areas. The IDT framework is concluded to be a good tool to further understand what can be done to facilitate diffusion. The study conclude that TAM can be used to identify challenges related to stakeholder perspective and perception also for non-information technology related technologies. Our study suggest that collaborative approach is needed in Sweden to resolve challenges for implementation. Recommendations for future research: The data is collected during a relatively short time period and limited number of interviews are conducted, therefore further studies are needed in the same area to bring more clarity to the FOWT diffusion mechanisms. We identify an opportunity for future research to further focus on the negative aspects of why the Swedish OWE industry perceives these factors as strong obstacles affecting the BIU. In parallel further of interest is to look at FOWT from a larger perspective such as Scandinavia and the understanding if cooperative activities can accelerate FOWT diffusion.

The increasing global participation of wind power in the overall generation ca- pacity makes it one of the most promising renewable resources. Advances in power electronics have enabled this market growth and penetration. Through a literature review, this work explores the challenges and opportunities presented by offshore wind farms, as well as the different solutions proposed concerning power electron- ics converters, collection and transmission schemes, as well as control and protection techniques. A novel power converter solution for the parallel connection of high power offshore wind turbines, suitable for HVDC collection and transmission, is presented. For the parallel operation of energy sources in an HVDC grid, DC link voltage con- trol is required. The proposed system is based on a full-power rated uncontrolled diode bridge rectifier in series with a partially-rated fully-controlled thyristor bridge rectifier. The thyristor bridge acts as a voltage regulator to ensure the flow of the desired current through each branch, where a reactor is placed in series for filtering of the DC current. AC filters are installed on the machine side to mitigate harmonic content. The mathematical modeling of the system is derived and the control design procedure is discussed. Guidelines for equipment and device specifications are pre- sented. Different setups for an experimental framework are suggested and discussed, including a conceptual application for hardware-in-the-loop real-time simulation and testing.

The offshore wind industry has advanced over the years and has attracted investments from oil & gas corporations. Europe is currently the main market for offshore wind development but in the heat of climate issues, there are calls from world bodies like The World Bank to develop this type of technology in other markets since it has been proven to be effective in displacing carbon emissions. This thesis explores the factors that could contribute to attract investments from the oil & gas industry into offshore wind development in emerging markets.  The thesis highlights the contributions oil & gas corporations have made towards the advancement of this technology. Further analysis is made on the weaknesses and strengths in developing this type of technology in selected countries which are categorised as emerging offshore wind markets to understand what is hindering the development of this energy in other markets.  Also, a direct question is posed to selected oil & gas corporations to ascertain what factors could attract them to invest in offshore wind development in these emerging markets. In the results, this thesis projects that oil & gas corporations will invest in these markets based on profitability, the need to affiliate with renewables to protect their businesses and as a safe measure against a decline in their core business of operation. The thesis also makes suggestions on ways emerging markets could attract investments from oil & gas corporations.

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Given the bleak current and projected global climate trends, society is transitioning the energy systems that we rely upon away from fossil fuel based systems to reduce global CO2 emissions. There are now well-established technologies for providing renewable electricity at utility scales, such as wind turbines and solar panels, being deployed at an ever increasing pace. However, solutions for decarbonizing other sectors where fossil fuels are harder to replace are still needed. Current strategies for reducing fossil fuel use in these sectors rely on replacing them with synthetic fuels instead are produced using renewable electricity, and can therefore be part of a net-zero emissions cycle. The focus of this thesis is to examine a novel class of wind energy systems suitable for powering these fuel synthesis processes. Alternative applications of the proposed systems include powering direct air CO2 capture systems to support negative emissions technology efforts. This work develops and presents numerical models for concepts hereafter referred to as mobile offshore wind energy systems (MOWESs). A MOWES is a wind energy system that operates offshore and is not intended to remain stationary during operation. MOWESs would operate far from shore, harnessing a part of the wind resource that would not otherwise be usable. No full- or large-scale MOWES has yet been developed, and there is little work on developing these concepts, even within academia. Steady-state power performance models of two MOWES concepts, namely unmoored floating offshore wind turbines and energy ships, are developed to support further research in this field. Model results suggest that each concept has unique pros and cons and no conclusion can be drawn as to which technology is more effiient overall. A key conclusion of this work is that unmoored floating wind turbines can generate more power by sailing at a constant speed rather than holding station. We also conclude that unmoored floating wind turbines designed for downwind operation can produce as much power as conventional stationary wind turbines given sufficiently high wind speeds. Further work must examine whether the advantages of these technologies are exploitable given realistic wind conditions and when considering the complicated dynamics of the system. / Graduate / 2023-08-09

Over the past decade, offshore wind has positioned itself as one of the most promising renewable energy markets. While this field is currently dominated by fixed-bottom wind turbines located within a limited depth range, floating turbines are showing promise as a way to capture the more developed wind profiles available in deeper waters. Currently, the main challenge with floating offshore wind is that the systems experience larger ultimate loads compared to fixed bottom turbines. These larger loads are caused by the increased motion inherent with floating structures. This study looks to analyze the effects that traditional and inerter based structural control methods can have on vibration reduction of floating offshore wind turbines. Models are developed adding tuned mass dampers (TMD) and tuned inerter dampers (TID) into the three main columns of a semisubmersible platform. Results showed that for free decay tests, heave and pitch root mean square (RMS) values were reduced significantly by the addition of passive structural control. The inerter based structural control consistently outperformed traditional TMD and also allowed for similar performance with significantly reduced physical mass values. For regular wave excitation both control methods resulted in significant reductions to the heave and pitch RMS values compared to the baseline, with the TID outperforming the TMD . And for an irregular wave analysis, it was found that both control configurations were still able to provide meaningful reductions to the baseline model. / Master of Science / Over the past decade, offshore wind has positioned itself as one of the most promising renewable energy markets. While this field is currently dominated by fixed-bottom wind turbines located within a limited depth range, floating turbines are showing promise as a way to capture the more developed wind profiles available in deeper waters. Currently, the main challenge with floating offshore wind is that the systems experience larger ultimate loads compared to fixed bottom turbines. These larger loads are caused by the increased motion inherent with floating structures. This study looks to analyze the effects that traditional and enhanced motion reduction technology can have on floating offshore wind turbines. Models are developed adding the traditional and enhanced motion reduction technology into the three main columns of a semisubmersible platform. Results showed that for several different tests, the motion reduction technology has a positive effect on the turbines. For test dropping the system from a set height, the motion reduction technology allowed the system to come to rest much faster. Moreover, the enhanced technology performed better than the traditional technology. The same results were found when the system was excited by simulated waves.

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Offshore wind in the United States is a rapidly growing industry. The development of both fixed bottom and floating platforms is important for the success of the industry. While monopiles are common substructures in Europe, the Atlantic Coast has a much greater risk for hurricanes. It is necessary to understand how extreme weather events will impact the structures. Meanwhile, floating offshore wind will be key for offshore wind development along the Pacific Coast, Hawaii, and Gulf of Maine. Before these projects can come to fruition, the cost of development must first decrease. A taut mooring system with multiline anchors may be able to reduce costs, specifically when deployed in deep water locations. This thesis considers these concerns for both the fixed bottom and floating wind developments. A parametric study is completed using OpenFAST for a variety of mooring systems. A taut multiline mooring system is designed for water depths ranging from 850 to 2000 meters. Further 850-meter designs explore how changing line properties impact the mooring line and multiline loading. Using these mooring designs, preliminary suction anchors are designed, focusing on the potential savings of decreasing the number of anchor installations from 3 single line anchors per turbine to 1 multiline anchor per turbine. Anchors are designed for a range of soil conditions to observe their impacts on anchor dimensions. For monopile design, four Atlantic Coast wind developments are chosen for design of monopiles at each site, using 50-year and 500-year storm conditions in the design process. These monopiles are designed using primarily hand calculations, with the assistance of OpenFAST to create a hub thrust power curve. The loads are then used to design monopile for a constant diameter and thickness from the transition piece to the mudline. The constant diameter monopiles are compared to a design that was complete for fatigue loading. In general, the fatigue loaded monopiles were required to be much larger, providing capacities larger than the monopiles designed for extreme storm conditions.