Yes / The fast‐growing offshore wind energy sector brings opportunities to provide a sustainable energy resource but also challenges in offshore wind turbine (OWT) operation and maintenance management. Existing operational simulation models assume deterministic input reliability and failure cost data, whereas OWT reliability and failure costs vary depending on several factors, and it is often not possible to specify them with certainty. This paper focuses on modelling reliability and failure cost uncertainties and their impacts on OWT operational and economic performance. First, we present a probabilistic method for modelling reliability data uncertainty with a quantitative parameter estimation from available reliability data resources. Then, failure cost uncertainty is modelled using fuzzy logic that relates a component's failure cost to its capital cost and downtime. A time‐sequential Monte Carlo simulation is presented to simulate operational sequences of OWT components. This operation profile is later fed into a fuzzy cost assessment and coupled with a wind power curve model to evaluate OWT availability, energy production, operational expenditures and levelised cost of energy. A case study with different sets of reliability data is presented, and the results show that impacts of uncertainty on OWT performance are magnified in databases with low components' reliability. In addition, both reliability and cost uncertainties can contribute to more than 10% of the cost of energy variation. This research can provide practitioners with methods to handle data uncertainties in reliability and operational simulation of OWTs and help them to quantify the variability and dependence of wind power performance on data uncertainties. / Engineering and Physical Sciences Research Council. Grant Number: EP/P009743/1

Addressing the decommissioning issues is vital to ensure a sustainable and effective process of such an essential part of the project life cycle. While there is a set of good practices and regulations that govern most of the decommissioning activities, the cable decommissioning issue is still in a big debate and often left abandoned at the seabed due to environmental concerns, as justified by most developers. This paper is aiming to understand the environmental and economic consequences of cable decommissioning. The available research papers and reports that are dealing with cable decommissioning issues have been reviewed. The cables are often decommissioned using similar methods to installation. However, there are no regulatory obligations to removing the cables in most countries. Cable installation will be associated with environmental impacts, but they are considered to be negligible. Additionally, Recycling cables’ copper is beneficial in both aspects environmentally and economically as copper prices are on the rise. A comparison between the ESs and decommissioning programs in a number of OWFSs have been conducted to understand the justification used for abandoning the cables. Most of the decommissioning reports have considered cable decommissioning to cause “considerable damage to seabed ecology”. However, that contradicts what was found in the ESs, where the impact level was considered negligible and anticipated to be similar to installation. It was unclear whether the abandonment of cables was driven by environmental considerations or not. A case study has been selected to compare cable and monopile decommissioning costs and the contribution of each component to the total decommissioning cost, including possible revenue generated from recycling. It was found that the cost-benefit of cable decommissioning is incomparable to monopile decommissioning as the latter is very costly, and the possible residual value is insignificant when compared to cables. Moreover, it is possible that the total cable decommissioning cost to be largely offset by the revenue generated from copper resell. Additionally, the cable decommissioning total cost can be almost paid by recycling cables if copper prices increase in the near future.

Sweden has a great potential for offshore wind energy production. As technology develops and policies change, construction of offshore wind farms in the country is likely to increase. The presented methodology is to apply MCDM and AHP methods in a GIS to produce an evaluation map of potential sites for offshore wind energy production.  The aim of this thesis was to determine what data is relevant and needed to translate Swedish and international standards and regulations regarding offshore wind farm siting into one or more layers of GIS data within the exclusive economic zone of Sweden. Furthermore the locations of the existing Areas of National Interests for offshore wind energy production have been evaluated using the evaluation map. The evaluation map has been obtained using several exclusionary criteria and buffer distances as well as four evaluation criteria. In addition, the results of this study have been used to calculate a potential net annual energy production for offshore wind energy in Sweden. The analysis considers some of the social, technical and environmental constraints present in offshore wind farm siting. The exclusion, buffer and evaluation criteria were determined in the initial literature review of previous studies on the topic. Datasets were collected from several different open online resources and Swedish government agencies, the analysis was performed using the QGIS software. To assess the results, the resulting evaluation map has been classified into four different categories: poor, average, good and excellent. The analysis shows that it is possible to translate Swedish and international standards into one layer of GIS data. Furthermore the results of this study show that 52% of the defined Areas of National Interest for offshore wind energy production should not be considered for wind farm siting according to the exclusion constraints, additionally only 19% of the Areas of National Interest for offshore wind energy production are classified as good or excellent. In contrast, 20.3% of the entire study area is deemed to be suitable for offshore wind farm siting, out of which 62.7% is classified as good or excellent. The potential net annual energy production has been estimated to be 56.1 TWh annually within the Areas of National Interest for offshore wind energy production and 915.3 TWh annually within the entire study area. / Sverige har en stor potential för produktion av havsbaserad vindkraft. När teknologin utvecklas och de politiska förutsättningar förändras, kommer konstruktionen av havsbaserad vindkraft i landet troligtvis öka. Den presenterade metodologin går ut på att använda MCDM och AHP metoder i ett GIS för att producera en utvärderingskarta för potentiella platser att producera havsbaserad vindenergi.  Målet med den här studien har varit att ta reda på vilken data som krävs och är relevant för att överföra svensk samt internationell standard och regler kring placeringen av havsbaserad vindkraft till ett eller flera lager av GIS data inom Sveriges exklusiva ekonomiska zon. Vidare har de existerande riksintressena för havsbaserad vindkraft utvärderats med hjälp av utvärderingskartan. Denna karta har blivit framtagen med hjälp av flertalet buffertzoner samt exkluderings- och fyra stycken utvärderingskriterier. Slutligen har studiens resultat används för att beräkna en potentiell årlig energiproduktion för offshore vindkraft i Sverige. Studien beaktar några av de sociala, tekniska och miljömässiga begränsningar som finns för havsbaserad vindenergi. Buffertzonerna samt exkluderings- och utvärderingskriterierna har bestämts med hjälp av en inledande litteraturstudie av tidigare forskning på ämnet. Den datan som använts i analysen har inhämtats från flera olika öppna onlineresurser samt från svenska myndigheter. Den efterföljande analysen har genomförts med hjälp av programmet QGIS. För att möjliggöra en kvantifiering av resultaten har utvärderings kartan omklassificerats till fyra olika kategorier: “poor”, “average”, “good” samt “excellent”. Studien visar att det är möjligt att överföra svensk samt internationell standard och regler till ett lager av GIS data. Resultatet visar att att enbart 48% av arean inom de definierade riksintressena för havsbaserad vindkraft bör beaktas vid allokering av havsbaserad vindenergi, enligt de begränsningar som definierats i denna studie. Vidare påvisar resultatet att enbart 19% av arean inom de utpekade riksintressena för vindkraft kan klassificeras som “good” eller “excellent”. Samtidigt påvisar studien att 20.3% av studieområdet bedöms som lämpligt för allokering av havsbaserad vindkraft, av dessa lämpliga områden klassificeras 62.7% som “good” och “excellent”. Den potentiella årliga energiproduktionen uppskattas till 56.1 TWh inom riksintressena för havsbaserad vindkraft samt till 915.3 TWh inom hela studieområdet.

The ocean has tremendous potential in terms of energy generation, and wave energy is especially promising. However, wave energy technology is still non-commercial. Along with ambitious renewable energy targets and investments, much is happening within the field and the wave energy converter developers CorPower Ocean intend to have their technology proven in the upcoming years. This study aims at investigating the value of commercial wave energy in an energy system. This is fulfilled by the possibilities of achieving 24/7 Carbon-free Energy with the wave energy technology from CorPower Ocean at the stage of commercialization. An energy system is modeled with wave energy, floating offshore wind energy, lithium-ion battery storage and the Portuguese national grid, supplying Northvolt’s and Galp’s future lithium conversion facility in Portugal. Different system configurations are compared based on three Key Performance Indicators: 24/7 Carbon-free Energy performance, system emission, and cost for the electricity consumer. In addition, a review of available financial support mechanisms for renewable energy technologies and especially wave energy is done to understand how such mechanisms can affect the economic feasibility of the energy system modeled. The wave energy technology from CorPower Ocean shows to have a high power output and 24/7 carbon-free Energy performance in this study. Although a combination of wave and floating offshore wind energy better ensure energy security with generation profiles that peak at different times, the modeling shows that a system with wave energy alone is preferred for supplying the facility with electricity both from an environmental and economic perspective. The economic feasibility of Lithium-ion battery storage in the system is uncertain and to achieve 24/7 Carbon-free Energy supply of the facility a longer duration storage solution is needed. The price for wave energy in this study is higher than for other commercial renewable energy technologies such as solar PV. However, based on the available financial support structures from governments and other stakeholders, wave energy technology has the potential to be competitive as soon as the technology is proven. / Energigenerering från våra hav har stor potential, inte minst från vågkraft. Trots att vågkraftstekniken ännu inte har nått ett kommersiellt stadie händer det mycket inom området i takt med fler ambitiösa miljökrav och investeringar. CorPower Ocean utvecklar vågkraftsteknik och planerar att ha sin teknik bevisad inom några år. Den här studien syftar till att undersöka värdet av kommersiell vågkraft, vilket uppfylls genom möjligheterna till förnybar el 24 timmar om dygnet med CorPower Ocean’s vågenergiomvandlare. Ett energisystem modelleras med vågkraft, flytande vindkraft, litium-jon batterier och det portugisiska elnätet för att försörja Northvolts och Galps planerade anläggning för litiumkonvertering i Portugal. Olika systemkonfigurationer är jämförda utifrån tre parametrar: 24/7 förnybar el prestation, systemutsläpp och elkostnad för konsumenten. I tillägg utförs en studie om vilka finansiella supportmekanismer som finns för hållbar energiteknik och speciellt för utvecklingen av vågkraft. Detta för att få insikt i om vågkraft kan få finansiellt stöd och konkurrera med andra förnybara energitekniker. Studien visar att vågkraftstekniken presenterar bra utifrån de tre parametrarna. Trots att en kombination av våg och flytande vindkraft ger bättre elsäkerhet med alternerande produktionskurvor visar modelleringen att ett system med endast vågkraft är att föredra både från ett ekonomiskt och ett miljöperspektiv. En investering av litium-jon batterier i energisystemet är tveksam och för att uppnå förnybar elförsörjning av anläggningen 24 timmar om dygnet krävs en energilagringsteknik som möjliggör lagring över längre perioder. Priset för vågkraft i studien är högre än för andra kommersiella förnybara energitekniker så som solpaneler. Baserat på det finansiella stöd som finns från myndigheter och andra intressenter så är det möjligt för vågkraften att bli konkurrenskraftig så fort tekniken är bevisad.

Submitted by Mateus Gomes (mateussg@msn.com) on 2018-05-25T17:01:45Z No. of bitstreams: 2 Dissertacao Mateus Gomes.pdf: 6830547 bytes, checksum: 47179b5d6a73fd8cdb299c49042f908c (MD5) Carta comprovante Mateus Gomes.jpg: 517376 bytes, checksum: 897b93ae582b7da42bf02be5122cf5a6 (MD5) / Approved for entry into archive by Milena Rubi ( ri.bso@ufscar.br) on 2018-06-04T13:13:11Z (GMT) No. of bitstreams: 2 Dissertacao Mateus Gomes.pdf: 6830547 bytes, checksum: 47179b5d6a73fd8cdb299c49042f908c (MD5) Carta comprovante Mateus Gomes.jpg: 517376 bytes, checksum: 897b93ae582b7da42bf02be5122cf5a6 (MD5) / Approved for entry into archive by Milena Rubi ( ri.bso@ufscar.br) on 2018-06-04T13:13:24Z (GMT) No. of bitstreams: 2 Dissertacao Mateus Gomes.pdf: 6830547 bytes, checksum: 47179b5d6a73fd8cdb299c49042f908c (MD5) Carta comprovante Mateus Gomes.jpg: 517376 bytes, checksum: 897b93ae582b7da42bf02be5122cf5a6 (MD5) / Made available in DSpace on 2018-06-04T13:13:34Z (GMT). No. of bitstreams: 2 Dissertacao Mateus Gomes.pdf: 6830547 bytes, checksum: 47179b5d6a73fd8cdb299c49042f908c (MD5) Carta comprovante Mateus Gomes.jpg: 517376 bytes, checksum: 897b93ae582b7da42bf02be5122cf5a6 (MD5) Previous issue date: 2018-02-26 / Não recebi financiamento / Electricity generation is a global challenge to be faced by several countries. This has led to the pursuit and development of new clean technologies to sustainable supply of the growing world demand for energy. Currently the main sources of renewable energy are: biomass, solar, geothermal, tidal, wind on and offshore (land and sea). Among these sources, wind energy presents worldwide growth and recently a significant increase in its use in the offshore segment. Brazil is among the ten largest onshore wind power producers in the world, however it does not have yet any offshore wind farms. The country has great potential for exploration of offshore wind power, since there are large population concentrations with increasing energy demands in coastal areas and an Exclusive Economic Zone (EEZ) of approximately 3.5 × 10^6 km^2. The objective of this work was to develop a methodology for the use of offshore wind energy through the proposal of an offshore wind farm on the Southeast coast of Brazil. The study was carried out for the Southeast region of Brazil in order to complement the energy matrix of the region, which today is mostly composed of hydroelectric power plants. The offshore wind farm proposal was carried out following the methodology developed in this work, which is based on two different types of data collection sources: ocean buoys and automatic meteorological stations. Weibull frequency distributions were calculated for each data collection source, power curve and capacity factor for the selected wind turbines in each locality, in order to identify the best location for the utilization of offshore wind energy in the Southeast region. The location of the collection point Cabo Frio 2 presented the best wind characteristics for offshore wind energy production, however its installation would require great complexity, so the selected collection point for the installation of an offshore wind farm in this work was the station A606 - Arraial do Cabo. The capacity factor calculated in the selected region was 0,51 for the wind turbine with lower power and 0,39 for the wind turbine with higher power, and the calculated wind speed at the reference height was 7,77 m/s, which is an adequate value for wind energy production. The wind farm proposed for this region is capable of supplying annually 604.461 MWh through 39 wind turbines, which are enough to supply the energy demand of approximately 115,870 residences during the whole year in a county located in the state of Rio de Janeiro. / A geração de energia elétrica é um desafio mundial a ser enfrentado por vários países. Isso tem levado a busca e desenvolvimento de novas tecnologias limpas para o abastecimento de forma sustentável da crescente demanda mundial por energia. As principais fontes de energia renováveis da atualidade são: biomassa, solar, geotérmica, maremotriz, eólica on e offshore (terra e mar). Dentre essas fontes, a energia eólica sinaliza crescimento mundial e recentemente um aumento significativo na sua utilização no segmento offshore. O Brasil está entre os dez maiores produtores mundiais de energia eólica onshore, entretanto ainda não possui empreendimentos eólicos offshore. O país possui grande potencial para exploração da fonte eólica offshore, visto que existem grandes concentrações populacionais com crescentes demandas energéticas em áreas costeiras e uma Zona Econômica Exclusiva (ZEE) de aproximadamente 3.5 × 10^6 km^2. O objetivo deste trabalho foi desenvolver uma metodologia para utilização da energia eólica offshore através da proposta de um parque eólico offshore no litoral Sudeste do Brasil. O estudo foi realizado para a região Sudeste do Brasil com intuito de complementar a matriz energética elétrica da região, que hoje é em sua maioria composta por hidroelétricas. A proposta do parque eólico offshore foi realizada seguindo a metodologia desenvolvida neste trabalho, que se baseia em dois diferentes tipos de fontes de coleta de dados: boias oceânicas e estações meteorológicas automáticas. Foram calculadas as distribuições de frequência de Weibull para cada fonte de coleta de dados, curva de potência e o fator de capacidade para os aerogeradores selecionados em cada localidade, com objetivo de identificar a melhor localização para utilização de energia eólica offshore na região sudeste. Os resultados mostram que, dentre os pontos de coleta de dados analisados, o local do ponto de coletas Cabo Frio 2 apresentou as melhoras características de ventos para exploração de energia eólica offshore, entretanto sua instalação demandaria grande complexidade, por isso o ponto de coleta selecionado para instalação de um parque eólico offshore neste trabalho foi a estação A606 - Arraial do Cabo. O fator de capacidade calculado na região selecionada foi de 0, 51 para o aerogerador com menor potência e 0,39 para o aerogerador com maior potência, e a velocidade no local calculada na altura de referência foi de 7,77 m/s, que é um valor adequado para produção de energia eólica. O parque proposto para esta região é capaz de fornecer anualmente 604.461 MWh, utilizando 39 aerogeradores, que são suficientes para abastecer cerca de 115.870 domicílios durante todo o ano para um município localizado no estado do Rio de Janeiro.

As has been the case for onshore wind systems, the environmental effects of offshore wind farms are expected to play an important part of the development of future large-scale wind energy systems. This paper presents a detailed review of the status of, and recent developments in, research on the environmental impacts of fixed and floating offshore wind turbine systems. The primary information that has been reviewed has come from European sources where there are a significant number of offshore installations, but some work on this subject has been carried out recently in the United States. Information, from an extensive review, is presented on the environmental impacts of fixed and floating offshore wind turbines on benthic organisms, fish, marine mammals, avian species and bats. The environmental impacts of fixed and floating systems are anticipated to vary due to multiple parameters that need to be taken into account when identifying environmental impacts. Additionally, there are variations in the impact throughout the lifecycle of the offshore wind turbines. The primary focus for this paper is on the environmental impacts through the scope of barrier and habitat impacts in addition to the anticipated avian and bat fatalities. A noise propagation model is used to determine the extent of effects due to the installation of fixed and floating support structures using piling installation methods. Finally, a summary of progress in all the major environmental impact areas is given along with recommendations for future research.

This study aims to explore the ability of a multi-criteria decision making with analytical hierarchy process (MCDM-AHP) model to emulate the results of a cost benefit analysis (CBA) model in the context of offshore wind farm siting within the Swedish exclusive economic zone (EEZ). The research question addressed is whether the MCDM-AHP analysis produces similar results to the CBA analysis. In addition to this, the strengths and weaknesses of each model is explored. The MCDM-AHP model employs the spatial criteria in a more basic manner compared to the CBA model, simplifying the evaluation process while still explaining 89.5% of the variation in the CBA model and defining similar areas as suitable. Thus, it can be concluded that the MCDM-AHP model adequately emulates the CBA model within the context of offshore wind farm siting within the Swedish EEZ. However, it is crucial to note that the two models produce outputs on different scales. While the CBA model provides levelized cost of energy (LCOE) values that can be thresholded for investment viability comparisons, the suitability score generated by the MCDM-AHP model remains a relative and arbitrary score within the model. Both models entail uncertainties, limiting their usage beyond making general assumptions or identifying areas of interest. The findings reveal that the CBA model demonstrates greater robustness when confronted with changes in spatial input parameters compared to the MCDM-AHP model. This discrepancy is attributed to the iterative computation process and consideration of flat cost inputs in the CBA model, whereas the MCDM-AHP model represents a linear combination of various spatial parameters. However, the calculated LCOE values in the CBA model are highly sensitive to changes in modeling assumptions regarding external parameters, resulting in significant linear variations. The LCOE values obtained from the CBA model baseline case fall within a range of 52.1 - 98.9 EUR/MWh, which aligns with similar studies, validating the CBA model. Nonetheless, caution should be exercised when considering these results as an accurate representation of the real world due to inherent uncertainties in cost inputs and the LCOE measure. The strengths of the MCDM-AHP model lie in its robustness when the order of relative importance remains stable for key spatial evaluators. It is sensitive to significant changes in water depth and wind speed, which heavily influence its output. The model's simplicity allows for a quick overview of the problem, but it requires assumptions that introduce uncertainties. Validation of the MCDM-AHP model using existing and planned offshore wind farms within the Swedish EEZ was possible but limited by the arbitrary scale and limited validation areas. The comparison between the two models could be enhanced with more comprehensive spatial and economic data for an in-depth CBA model, which could serve as a ground truth for the MCDM-AHP model. Nevertheless, the comparison made in this study considers the CBA model to be closer to the truth, acknowledging the underlying assumptions that should be considered during evaluation. In conclusion, within the context of offshore wind farm siting, the MCDM-AHP model produces outputs that are similar to the CBA model.

There has recently been an increased interest in hydrogen, both as a solution for seasonal energy storage but also for implementations in various industries and as fuel for vehicles. The transition to a society less dependent on fossil fuels highlights the need for new solutions where hydrogen is predicted to play a key role. This project aims to investigate technical and economic outcomes of different strategies for production and storage of hydrogen based on hydrogen demand and source of electricity. This is done by simulating the operation of different systems over a year, mapping the storage level, the source of electricity, and calculating the levelized cost of hydrogen (LCOH). The study examines two main cases. The first case is a system integrated with offshore wind power for production of hydrogen to fuel the operations in the industrial port Gävle Hamn. The second case examines a system for independent refueling stations where two locations with different electricity prices and traffic flows are analyzed. Factors such as demand, electricity prices, and component costs are investigated through simulating cases as well as a sensitivity analysis. Future potential sources of income are also analyzed and discussed. The results show that using an alkaline electrolyzer (AEL) achieves the lowest LCOH while PEM electrolyzer is more flexible in its operation which enables the system to utilize more electricity from the offshore wind power. When the cost of wind electricity exceeds the average electricity price on the grid, a higher share of wind electricity relative to electricity from the grid being utilized in the production results in a higher LCOH. The optimal design of the storage depends on the demand, where using vessels above ground is the most beneficial option for smaller systems and larger systems benefit financially from using a lined rock cavern (LRC). Hence, the optimal design of a system depends on the demand, electricity source, and ultimately on the purpose of the system. The results show great potential for future implementation of hydrogen systems integrated with wind power. Considering the increased share of wind electricity in the energy system and the expected growth of the hydrogen market, these are results worth acknowledging in future projects.