Structural health monitoring of offshore wind turbines: A review through the Statistical Pattern Recognition Paradigm

Offshore Wind has become the most profitable renewable energy source due to the remarkable development it has experienced in Europe over the last decade. In this paper, a review of Structural Health Monitoring Systems (SHMS) for offshore wind turbines (OWT) has been carried out considering the topic as a Statistical Pattern Recognition problem. Therefore, each one of the stages of this paradigm has been reviewed focusing on OWT application. These stages are: Operational Evaluation; Data Acquisition, Normalization and Cleansing; Feature Extraction and Information Condensation; and Statistical Model Development. It is expected that optimizing each stage, SHMS can contribute to the development of efficient Condition-Based Maintenance Strategies. Optimizing this strategy will help reduce labor costs of OWTs׳ inspection, avoid unnecessary maintenance, identify design weaknesses before failure, improve the availability of power production while preventing wind turbines׳ overloading, therefore, maximizing the investments׳ return. In the forthcoming years, a growing interest in SHM technologies for OWT is expected, enhancing the potential of offshore wind farm deployments further offshore. Increasing efficiency in operational management will contribute towards achieving UK׳s 2020 and 2050 targets, through ultimately reducing the Levelised Cost of Energy (LCOE)

Maintenance Optimization and Inspection Planning of Wind Energy Assets: Models, Methods and Strategies

Designing cost-effective inspection and maintenance programmes for wind energy farms is a complex task involving a high degree of uncertainty due to diversity of assets and their corresponding damage mechanisms and failure modes, weather-dependent transport conditions, unpredictable spare parts demand, insufficient space or poor accessibility for maintenance and repair, limited availability of resources in terms of equipment and skilled manpower, etc. In recent years, maintenance optimization has attracted the attention of many researchers and practitioners from various sectors of the wind energy industry, including manufacturers, component suppliers, maintenance contractors and others. In this paper, we propose a conceptual classification framework for the available literature on maintenance policy optimization and inspection planning of wind energy systems and structures (turbines, foundations, power cables and electrical substations). The developed framework addresses a wide range of theoretical and practical issues, including the models, methods, and the strategies employed to optimise maintenance decisions and inspection procedures in wind farms. The literature published to date on the subject of this article is critically reviewed and several research gaps are identified. Moreover, the available studies are systematically classified using different criteria and some research directions of potential interest to operational researchers are highlighted

Failure mode identification and end of life scenarios of offshore wind turbines: a review

In 2007, the EU established challenging goals for all Member States with the aim of obtaining 20% of their energy consumption from renewables, and offshore wind is expected to be among the renewable energy sources contributing highly towards achieving this target. Currently wind turbines are designed for a 25-year service life with the possibility of operational extension. Extending their efficient operation and increasing the overall electricity production will significantly increase the return on investment (ROI) and decrease the levelized cost of electricity (LCOE), considering that Capital Expenditure (CAPEX) will be distributed over a larger production output. The aim of this paper is to perform a detailed failure mode identification throughout the service life of offshore wind turbines and review the three most relevant end of life (EOL) scenarios: life extension, repowering and decommissioning. Life extension is considered the most desirable EOL scenario due to its profitability. It is believed that combining good inspection, operations and maintenance (O&M) strategies with the most up to date structural health monitoring and condition monitoring systems for detecting previously identified failure modes, will make life extension feasible. Nevertheless, for the cases where it is not feasible, other options such as repowering or decommissioning must be explored

Long-term research challenges in wind energy – a research agenda by the European Academy of Wind Energy

The European Academy of Wind Energy (eawe), representing universities and institutes with a significant wind energy programme in 14 countries, has discussed the long-term research challenges in wind energy. In contrast to research agendas addressing short- to medium-term research activities, this eawe document takes a longer-term perspective, addressing the scientific knowledge base that is required to develop wind energy beyond the applications of today and tomorrow. In other words, this long-term research agenda is driven by problems and curiosity, addressing basic research and fundamental knowledge in 11 research areas, ranging from physics and design to environmental and societal aspects. Because of the very nature of this initiative, this document does not intend to be permanent or complete. It shows the vision of the experts of the eawe, but other views may be possible. We sincerely hope that it will spur an even more intensive discussion worldwide within the wind energy community

Analysis of Greenhouse Gas Emissions from Offshore Wind Turbines

Renewable energy resources such as offshore wind turbines are considered as if they do not emit greenhouse gas emissions, as greenhouse gases are not emitted from these resources during electricity generation. However, throughout the various lifecycle stages of offshore wind turbines, significant levels of greenhouse gases could be emitted. To this end, we seek to analyse the greenhouse gas emissions from offshore wind turbines. The core objective of the thesis is to assess the major factors that result in greenhouse gas emissions from offshore wind turbines. Specifically, we study these factors from a lifecycle perspective. In this light, we investigate the major factors at each lifecycle stage of offshore wind turbines that result in greenhouse gas emissions. Moreover, we lay out several recommendations so that offshore wind turbines that are currently deployed or will be designed in the future can result in significantly lower greenhouse gas emissions

A model for availability growth with application to new generation offshore wind farms

A model for availability growth is developed to capture the effect of systemic risk prior to construction of a complex system. The model has been motivated by new generation offshore wind farms where investment decisions need to be taken before test and operational data are available. We develop a generic model to capture the systemic risks arising from innovation in evolutionary system designs. By modelling the impact of major and minor interventions to mitigate weaknesses and to improve the failure and restoration processes of subassemblies, we are able to measure the growth in availability performance of the system. We describe the choices made in modelling our particular industrial setting using an example for a typical UK Round III offshore wind farm. We obtain point estimates of the expected availability having populated the simulated model using appropriate judgemental and empirical data. We show the relative impact of modelling systemic risk on system availability performance in comparison with estimates obtained (Lesley Walls) from typical system availability modelling assumptions used in offshore wind applications. While modelling growth in availability is necessary for meaningful decision support in developing complex systems such as offshore wind farms, we also discuss the relative value of explicitly articulating epistemic uncertainties

Ocean Energy in Belgium - 2019

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The implications of energy systems for ecosystem services: A detailed case study of offshore wind

Globally, the deployment of offshore wind is expanding rapidly. An improved understanding of the economic, social and environmental impacts of this sector, and how they compare with those of other energy systems, is therefore necessary to support energy policy and planning decisions. The ecosystem services approach provides a more holistic perspective of socio-ecological systems than traditional environmental impact assessment. The approach also makes possible comparisons across disparate ecological communities because it considers the societal implications of ecological impacts rather than remaining focused on specific species or habitats. By reporting outcomes in societal terms, the approach also facilitates communication with decision makers and the evaluation of trade-offs. The impacts of offshore wind development on ecosystem services were assessed through a qualitative process of mapping the ecological and cultural parameters evaluated in 78 empirical studies onto the Common International Classification for Ecosystem Services (CICES) framework. The research demonstrates that a wide range of biophysical variables can be consistently mapped onto the CICES hierarchy, supporting development of the ecosystem service approach from a broad concept into an operational tool for impact assessment. However, to improve confidence in the outcomes, there remains a need for direct measurement of the impacts of offshore wind farms on ecosystem services and for standardised definitions of the assumptions made in linking ecological and cultural change to ecosystem service impacts. The process showed that offshore wind farms have mixed impacts across different ecosystem services, with negative effects on the seascape and the spread of non-native species, and positive effects on commercial fish and shellfish, potentially of most significance. The work also highlighted the need for a better understanding of long term and population level effects of offshore wind farms on species and habitats, and how these are placed in the context of other pressures on the marine environment