MS6.1 - Dynamic of marine energy systems

The increased availability of solar energy potential, especially in southern latitudes as in the Mediterranean Sea, constitutes a strong motivation for the design and development of float-ing offshore solar energy platforms suitable for deployment and operation in the sea envi-ronment; see, e.g. Ref.[1]. In this work a novel Boundary Element Method [2] is used for the hydrodynamic analysis of floating twin-hull structures carrying photovoltaic panels on the deck. The method supports the investigation of wave responses and their effects on solar power performance in variable bathymetry regions. A boundary integral formulation, in-volving simple singularities, is applied in the vicinity of the floating body for the representation of the near field, in conjunction with suitable models for the treatment of conditions at infinity of the considered diffraction/radiation problems in variable bathymetry regions. With the aid of systematic comparisons, the effects of the bottom slope and curvature on the hydrodynamic characteristics (hydrodynamic coefficients and responses) of the floating bodies are shown and discussed. Finally, the effects of waves on the floating PV performance are presented, indicating significant variations of the performance index depending on the sea state. For the demonstration of the studied system preliminary results from study concerning the performance of the considered modules(s) in selected areas are discussed. REFERENCES: [1] Diendorfer C., Haider M., Lauermann M., 2014, Performance analysis of offshore so-lar power plants. Energy Procedia 49: 2462–2471 [2] Magkouris A., Belibassakis K, Rusu E, 2021, Hydrodynamic Analysis of Twin-Hull Structures Supporting Floating PV Systems in Offshore and Coastal Regions, Energies 14 (18), 5979.

At present, the fatigue-life design of Offshore Wind Turbines (OWTs) is based on design assumptions accounting for significant uncertainties both on loading and fatigue-resistance of different vulnerable structural details. Monitoring of strain histories can potentially have a significant positive impact when estimating the remaining life of Offshore Wind Turbines (OWTs), as the uncertainties are reduced. However, strain-based monitoring approaches present the important drawbacks, the first of them being that only instrumented locations can be assessed and the second that there tend to be accessibility issues associated with the installation process. In this paper, the initial results of a novel methodology developed to estimate strain time histories are presented. The underlying idea of such approach is to combine an updated FE model with the vibration response histories acquired with only a few sensors to estimate the strain histories at any location of an OWT.

Whilst real-sea demonstrations may steal the spotlight, an ocean energy test centre does a lot more than just provide sea space for testing. The challenges of progressing the ocean energy sector toward commercialisation span a multitude of regulatory, financial, environmental, and technical issues not just focused at full-scale prototype demonstration, but at component and sub-system level as well. Combined with a need for transition away from oil and gas, ‘learning by doing’ is vital to identify opportunities to improve as is sharing skills and experience across offshore industries. Test centres give rise to an array of RD&I projects aimed to support and develop an industry. EMEC is the world’s first and only IECRE Renewable Energy Testing Laboratory (RETL) for ocean energy and is an accredited laboratory (ISO/IEC 17025) and inspection body (ISO/IEC 17020). EMEC has been involved in projects spanning environmental monitoring, biofouling, corrosion, moorings, subsea cabling, reliability, performance testing, certification and decommissioning. In the context of structural dynamics, EMEC supports numerous projects which will be discussed during this session. The session will discuss the results of acoustic monitoring of marine populations to understand how they respond to marine energy devices and collision risk modelling and monitoring. The impact of turbulence on tidal devices and its influence on power performance is also being investigated as is research involving physical mechanical moving loads from marine applications such as devices, cables and infrastructure. As a test centre, we identify real-world problems and investigate their resolution from dynamic cable monitoring solutions to fatigue experienced on emergency disconnect systems. The projects ongoing at EMEC and research collaboration opportunities will be discussed with an emphasis on marine renewables and offshore wind. As a not-for-profit organisation, the experience and challenges from this research is fed directly into the marine energy community and other test centres to instigate further collaboration, innovation and knowledge sharing. The effect is then cyclical, and we’ve seen several joint transnational projects supporting the development of wave and tidal energy technologies (e.g. OceanDEMO and Blue-GIFT) evolve from knowledge-sharing collaborative networking. Beyond this, as well as being a catalyst for ocean energy development, the existence of test centres acts as a magnet for wider low carbon innovations. For example Microsoft tested an underwater data centre at EMEC and there are numerous projects in Orkney focused on developing a local hydrogen economy to decarbonise fuel for transport. Test centres support economic development, with developer and supply chain companies clustering around the test centre, and create well-paid jobs in the community. EMEC has also help instigate major shifts in policy at UK level with the inclusion of ring-fenced support for marine energy.