Browsing by Author "Martinez-Luengo, Maria"

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    The end of the line for today's wind turbines
    (Elsevier, 2016-06-20) Kolios, Athanasios; Martinez-Luengo, Maria
    We need to start thinking today about the future of our wind turbines, according to Dr Athanasios Kolios and María Martínez-Luengo from Cranfield University. EDF's recent announcement that they will extend the life of 4 of their 8 UK-based nuclear power plants has focussed analyst's minds on the pros and cons of extending service life. There are numerous cost and engineering issues at play here. These obviously include balancing the initial investment cost against profits already made and the potential decreasing efficiency alongside the increasing maintenance costs in an ageing facility. The issues cut across the whole energy sector, but they aren’t something many of our renewable technologies have yet had to face.
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    Failure mode identification and end of life scenarios of offshore wind turbines: a review
    (MDPI, 2015-08-07) Martinez-Luengo, Maria; Kolios, Athanasios
    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.
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    Guidelines and cost-benefit analysis of the structural health monitoring implementation in offshore wind turbine support structures
    (MDPI, 2019-03-26) Martinez-Luengo, Maria; Shafiee, Mahmood
    This paper investigates how the implementation of Structural Health Monitoring Systems (SHMS) in the support structure (SS) of offshore wind turbines (OWT) affects capital expenditure (CAPEX) and operational expenditure (OPEX) of offshore wind farms (WF). In order to determine the added value of Structural Health Monitoring (SHM), the balance between the reduction in OPEX and the increase in CAPEX is evaluated. In this paper, guidelines for SHM implementation in offshore WF are developed and applied to a baseline scenario. The application of these guidelines consist of a review of present regulations in the United Kingdom and Germany, the development of SHM strategy, where the first stage of the Statistical Pattern Recognition (SPR) paradigm is explored, failure modes that can be monitored are identified, and SHM technologies and sensor distributions within the turbines are described for a baseline scenario. Furthermore, an inspection strategy where the different structural inspections to be carried out above and below water is also developed, together with an inspection plan for the lifetime of the structures, for the aforementioned baseline scenario. Once the guidelines have been followed and the SHM and inspection strategies developed, a cost-benefit analysis is performed on the baseline case (10% instrumented assets) and three other scenarios with 20%, 30% and 50% of instrumented assets. Finally, a sensitivity analysis is conducted to evaluate the effects of SHM hardware cost and the time spent in completing the inspections on OPEX and CAPEX of the WF. The results show that SHM hardware cost increases CAPEX significantly, however this increase is much lower than the reduction in OPEX caused by SHM. The results also show that an increase in the percentage of instrumented assets will reduce OPEX and this reduction is considerably higher than the cost of SHM implementation.
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    Parametric FEA modelling of offshore wind turbine support structures: towards scaling-up and CAPEX reduction
    (Elsevier, 2017-05-26) Martinez-Luengo, Maria; Kolios, Athanasios; Wang, Lin
    Parametric Finite Element Analysis (FEA) modelling is a powerful design tool often used for offshore wind. It is so effective because key design parameters (KDPs) can be modified directly within the python code, to assess their effect on the structure’s integrity, saving time and resources. A parametric FEA model of offshore wind turbine (OWT) support structures (consisting of monopile (MP), soil-structure interaction, transition piece (TP), grouted connection (GC) and tower) has been developed and validated. Furthermore, the different KDPs that impact on the design and scaling-up of OWT support structures were identified. The aim of the analyses is determining how different geometry variations will affect the structural integrity of the unit and if these could contribute to the turbine’s scale-up by either modifying the structure’s modal properties, improving its structural integrity, or reducing capital expenditure (CAPEX). To do so, three design cases, assessing different KDPs, have been developed and presented. Case A investigated how the TP’s and GC’s length influences the structural integrity. Case B evaluated the effect of size and number of stoppers in the TP, keeping a constant volume of steel; and Case C assessed the structure’s response to scour development. It is expected that this paper will provide useful information in the conceptual design and scale-up of OWT support structures, helping in the understanding of how KDPs can affect not only the structure’s health, but also its CAPEX.
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    Structural health monitoring of offshore wind turbines: A review through the Statistical Pattern Recognition Paradigm
    (Elsevier, 2016-06-09) Martinez-Luengo, Maria; Kolios, Athanasios; Wang, Lin
    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).