Offshore floating wind turbine (FWT) provides an efficient solution to address climate challenge. Integrated analysis of FWT is vital to reduce the uncertainties in design and save costs. In the field, seabed trenches dramatically increase the failure risks of mooring system and raise operation and maintenance costs. However, the mooring line-seabed interaction related to soil erosion and trench development is not considered in design code (DNVGL-ST-0119, 2018). Thus, two objectives of this project are: 1. reveal the trigger factor for seabed trenching due to the mooring line-soil interaction; simulate the trench development with time. 2. establish the macro element model considering seabed trenching process; integrate the model into the integrated analysis tool of FWTs, e.g., SESAM. A total of 3 packages are designed comprehensively. In the seabed trenching package, conduct 1g erosion test to reveal the trigger factor for seabed trenching (WP1.1). Then propose the soil erosion model based on analytical analysis based on 1g erosion test (WP1.2). Finally, the trench development will be simulated by the trench profile model (WP1.3). In the mooring line-seabed package, get the chain resistance by 1g result (WP2.1); establish the macro element model (WP2.2); considering seabed trenching process, which can consider the soil degradation, erosion, removal (WP2.3). In integrated analysis package, integrate the model into the integrated analysis tool of FWTs, e.g., SESAM (WP3). The new development of the soil erosion model, seabed trench model and macro element of mooring line soil interaction are the new computation tool for scientific analysis. Integrated analysis tool for FWT will be an important and powerful tool for FWT analysis considering mooring line-soil interaction, which will contribute to standards’ setting. This will be a groundbreaking progress and will fill the gaps in the norms and standards (DNVGL-ST-0119).

TAILWIND-UP-HopOn will expand the existing knowledge on the design of station-keeping systems for floating wind energy on the Atlantic coast, making it publicly available to accelerate deployment. At present, only pilot projects have been implemented off the Portuguese coast, as large-scale infrastructures remain cost-prohibitive. Advancing knowledge to reassess and refine anchor system design methods and practices towards cost reduction is therefore critical. TAILWIND station-keeping technologies will be investigated with a focus on the specific conditions of the northern Portuguese Atlantic coast. The TAILWIND methodology will also be expanded by including different soil stress paths, scour analysis, and reliability studies. After the definition and characterization of the metocean and geotechnical scenarios including climate change, and the evaluation of the hydrodynamic response of selected technologies, TAILWIND-UP-HopOn will analyse the impact of vertical loads on the cyclic behaviour of soils subjected to multidirectional horizontal loading. The project will also assess whether scour and liquefaction of foundation soils, due to the vibration of mooring lines, significantly affect the performance of station-keeping systems for floating wind turbines. These inputs will be integrated into a numerical analysis of the soil-anchor system to identify new failure modes, reduce their associated risk, increase design reliability, and ultimately optimise its design. Integrating the data generated by the Hop On team with TAILWIND consortium outputs will contribute to the development of sustainable and efficient station-keeping systems for floating wind, tailored to the specific conditions of North Atlantic Coast. With this extension, the new TAILWIND project will impact the three main areas in Europe for offshore wind development: the North Sea, the Mediterranean Sea, and the Atlantic Ocean, while mobilising Portuguese excellence in a strategic area for the country.

POSEIDON brings together an interdisciplinary and intersectoral team to deliver a professionally trained next-generation network of Doctoral Candidates to develop a step change in our capacity to identify, map, assess and predict offshore geohazards and in turn produce ground-breaking methods to prevent, mitigate and boost the resilience of current offshore infrastructure under a changing climate. The consortium is formed by experts across EU countries with universities, research institutions, industry partners and a government body to cover a full training programme on scientific and transferable skills. The programme will undertake critical research across scales (from micro to macro) for seeking the inner links and differences, with an eventual aim to ascertain the pathways and grow our capacity for the enhancement of the existing and the robust development of new offshore infrastructure in the frame of safety and resiliency. In addition to the informed design and implementation of the novel physical/numerical modelling and lab studies, our approach is unique in the solid integration and utilisation of state-of-the-art data science technologies (e.g., data mining, machine learning, etc.) to their full potential. Only through this systematic approach, we can achieve the objectives of understanding the impact of offshore geohazards on our offshore critical infrastructures (OCIs) and developing novel models, tools and designs for future OCIs, such as, wind turbines, pipelines and cables. The Doctoral Candidates will enjoy a highly integrated, interdisciplinary and intersector training environment, enriched through secondments with the network of non-academics. POSEIDON enables critical learning across all training aspects to ensure that comprehensive, robust and implementable solutions are obtained and validated to face the OCIs climate-resilient building.