Europe is a leader in offshore wind energy. Currently nearly all of the EU's offshore wind farms are bottom-fixed and located in the North and Baltic Sea, where wind conditions are ideal and water depths are low. Further increasing offshore renewable energy generation is key to meeting renewable energy policy goals. One of the most attractive technologies to generate renewable energy in deep waters is Floating Offshore Wind (FOW). In fact, FOW foundations have emerged as a potentially more cost-effective alternative to fixed-bottom offshore wind farms, particularly for greater depths where the latter become less viable. With the ability to generate power in deep waters, many envision floating offshore wind farms to become a cornerstone of the future green energy supply. FOW however remains a novel technology, with few demonstrators in operation to date; moreover, Floating Offshore Wind Turbines (FOWTs) have not converged toward a single archetype, with recent surveys indicating for example that over 50 different floater concepts are currently under investigation. Complexity further increases when farm level is considered, in which many unknowns are still to be solved due to the lack of field application.
Within this context, some key areas for improvement can be highlighted. Regarding turbine technology, FOWTs seem particularly suited to benefit from the general design trend of rotor upscaling to reduce the Levelized Cost of Energy (LCOE). In fact, they not only benefit from higher gross capacity factors, but the floating foundation and installation cost per-kW are also greatly impacted. Installation of very large machines is also more logical offshore, where there are less transport restrictions. Increasing the size of FOWTs, however, also poses many challenges: the increases in mass, rotor area, and hub height induce significant loads and overturning moments and can pose a serious issue in terms of load amplification on the tower and support structure, which thus needs to be redesigned accordingly. Reducing raw material use on these large offshore structures can in turn increase competitiveness and reduce the environmental impact of this form of energy. An expert survey expects the mean annual wind speed of FOWT installation sites in 2035 to be higher than that of current fixed-bottom offshore projects. While this trend seems reasonable in the near future, as high wind speed areas will be exploited first, things may change substantially in a long-term scenario as FOWTs are installed in Mediterranean EU countries and other sea basins in the EU, where wind speeds are lower. Tailoring FOWT designs to these conditions can help ensure that these countries meet their renewable energy generation goals.
From a technical standpoint, it is important to recognise that a FOWT is a highly complex system, subject to wind, waves and sea currents. As the FOWT moves, the apparent wind speed on the rotor may cause the controller to react, triggering instabilities. Traditional onshore control techniques can be adapted to avoid triggering these instabilities but generally lead to suboptimal rotor control. Improvements in this field could be a key catalyst of FOW technology. Moreover, FOWT structures are large, and their impact on the marine environment is currently largely unknown. These systems are envisioned to be deployed in large wind farms and may have to compete for space with other offshore activities such as fishing, shipping and tourism. Efficient use of the offshore space is key, and this issue can only be tackled from a farm-perspective. Innovations in farm control, mooring technology and cabling must be pursued to reach this goal. In summary, increasing the energy density of FOWT deployments, reducing the use of raw materials while minimising social and environmental impact and maximising energy production and wind farm density is a multi-disciplinary problem that cannot be tackled effectively from any single viewpoint. In fact, a multi-platform approach is required to develop and integrate innovative technologies sustainably into a FOWT context.
The overarching goal of FLOATFARM is to significantly advance the maturity of floating offshore wind (FOW) technology by increasing energy production and achieving significant cost reductions at all levels within the design and implementation phases. Ultimately, FLOATFARM aims to contribute to decreasing the negative environmental impacts on marine life and to enhancing the public acceptability of floating offshore wind farms. To this end, several critical technologies have been identified as key catalysts to improve the performance at both turbine and farm level through advancements in rotor technology, mooring and anchoring, farm deployment and control strategies. FLOATFARM adopts a holistic approach that combines innovative designs with demonstration in real-world marine environment, experimental demonstration at laboratory scale and modelling with a suite of beyond state-of-the-art numerical analysis tools. In order to achieve this goal, five specific objectives (SOs) will be pursued. Addressing these SOs will require interactive collaboration between academic and industrial partners within the consortium, as well as the combined use of multi-fidelity simulations and multi-scale experimental validation, with special focus on systematic validation in a one of a kind open-sea laboratory.
SO1: Lower the LCOE of FOWTs by improving efficiency and reducing system mass, installation and operational costs through the demonstration of innovative generator, rotor and control technologies within a holistic optimisation framework.
SO2: Improve FOWT marine component design through multi-scale demonstration of innovative technologies in laboratory, numerical and real-world environments.
SO3: Demonstrate offshore farm-level performance optimisation through the application of active wake mixing and turbine synchronicity to improve farm sub-cluster performance.
SO4: Demonstrate shared mooring and anchoring concepts for the reduction of material use and the improved coupled dynamic behaviour of offshore wind farms.
SO5: Reduce negative environment impact of FOWT substructures, mooring and cabling at both local and regional scale on marine flora and fauna and improve social perception for floating offshore wind.
