Suchergebnisse

This is the final version. Available on open access from MDPI via the DOI in this record. ; Operation and maintenance constitute a substantial share of the lifecycle expenditures of an offshore renewable energy farm. A noteworthy number of methods and techniques have been developed to provide decision-making support in strategic planning and asset management. Condition monitoring instrumentation is commonly used, especially in offshore wind farms, due to the benefits it provides in terms of fault identification and performance evaluation and improvement. Incorporating technology advancements, a shift towards automation and digitalisation is taking place in the offshore maintenance sector. This paper reviews the existing literature and novel approaches in the operation and maintenance planning and the condition monitoring of offshore renewable energy farms, with an emphasis on the offshore wind sector, discussing their benefits and limitations. The state-of-the-art in industrial condition-based maintenance is reviewed, together with deterioration models and fault diagnosis and prognosis techniques. Future scenarios in robotics, artificial intelligence and data processing are investigated. The application challenges of these strategies and Industry 4.0 concepts in the offshore renewables sector are scrutinised, together with the potential implications of early-stage project integration. The identified technologies are ranked against a series of indicators, providing a reference for a range of industry stakeholders. ; Engineering and Physical Sciences Research Council (EPSRC) ; European Union Horizon 2020

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record ; The multi-chamber Oscillating Water Column (OWC) device has recently become more attractive due to its potential high efficiency. In this paper, the hydrodynamic performance of a single-, dual- and triple-chamber OWC-breakwater are investigated experimentally. In the first instance, quantitative comparisons are implemented to understand the hydrodynamic performance of multi-chamber OWC-breakwaters. Specific attention has been dedicated to the hydrodynamic performance of capture width ratio (CWR), reflection coefficient, transmission coefficient, dissipation coefficient and effective frequency bandwidth. The investigation identified various findings that can be summarized as follows: i) hydrodynamic interactions between chambers in the multi-chamber OWC device has improved wave power extraction characteristics; ii) comparing with the conventional pontoon breakwater, the multi-chamber OWC-breakwater showed better wave attenuation performance in longer waves; iii) wave steepness is important for evaluating the performance of the multiple-chamber OWC-breakwater device; and iv) the implementation of the multi-chamber scheme broadens the effective frequency bandwidth (satisfied the condition of KT 0.2) of OWC-breakwater. ; Key Program for International Scientific and Technological Innovation Cooperation between Governments ; National Natural Science Foundation of China ; China Postdoctoral Science Foundation

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record ; This paper uses a fully nonlinear model to comprehensively explore the coupled effects caused by the system integration between an offshore wind turbine and a heaving buoy wave energy converter. Parameters of the study include the pitch motion of wind turbine, the tension on the mooring line, the contact pressure between these two devices, and the energy absorbed by power take-off (PTO) system. Results demonstrated that the buoy stabilises/reduces the pitch motion of wind turbine when its metacentric height is positive. A buoy with a negative metacentric height will increase the pitch amplitude of wind turbine and the tension of the mooring line, which is undesirable. The relative vertical motion between heaving buoy and spar could buffer their maximum contact pressure. The Coulomb PTO could offer a higher peak output power of WEC than the linear PTO. The relationship between contact pressure and WEC peak power is quantified to inform the PTO design. The wind/wave device is evaluated at a representative site with suitable wind and wave conditions off the US West Coast. The WEC does significantly reduce the wind turbine pitch motion by at least 60%/50% for the modelled average/max wave conditions with increased power production (14%/80%). ; Engineering and Physical Sciences Research Council (EPSRC) ; European Union Horizon 2020

This is the final version of the article. Available from Elsevier via the DOI in this record ; The growing marine renewable energy sector has led to a demand for increasingly compliant mooring systems. In response, several innovative mooring tethers have been proposed demonstrating potential customisation to the stiffness profi le and reduced peak mooring loads. Many of these novel systems utilise materials in a unique application within the challenging marine environment and their long term durability remains to be proven. This paper presents a multifaceted investigation into the durability of a novel polyester mooring tether with an elastomeric core. Laboratory based functionality tests are repeated on tether assemblies following a 6 month sea deployment. Results show a 45% average increase in dynamic axial stiffness. This is supported by high tension laboratory based fatigue endurance tests showing a peak increase in dynamic axial stiffness of 42%. Sub-component material tests on the core elastomer support the assembly tests, separately demonstrating that certain aspects of tether operation lead to increased material sample stiffness. The average increase in material radial compressive stiffness is 22% and 15% as a result of marine ageing and repeated mechanical compression respectively; these are the fi rst results of this type to be published. The performance durability characterisation of the tether establishes the mooring design envelope for long-term deployment. This characterisation is crucial to ensure reliable and effective integration of novel mooring systems into offshore engineering projects. ; This work was supported by the Engineering and Physical Sciences Research Council, via a PhD funded through the SuperGen UKCMER programme. Additional funding was provided by the EC through the MARINET FP7 programme which funded access to the IFREMER Materials in a Marine Environment Laboratory for two weeks. The P1 Tether series were developed with assistance from Lankhorst Ropes and HEFCE through the HE Innovation Fund. The P3 and P4 Tether series were developed with Lankhorst Ropes as part of the OPERA Project, funded by the European Union's Horizon 2020 programme under grant agreement No 654.444.