Background
Offshore wind power consists of generating electricity through wind farms installed at sea. In relatively shallow waters (up to 50 meters depth), fixed-foundation wind turbines are employed, essentially preserving the structural features of onshore twins. To increase the installation depths, floating structures have been considered. Such platforms are stabilized by moorings and anchors that flexibly connect them to fixed points on the seabed, thus safely providing support in up to 300 meters of water depth (Lauria et al. 2024). Floating wind farms comprise wind turbines that are placed on platforms, and connected to an offshore substation through submarine cables to transmit the generated electricity (Figure 1). Such complexity reflects into its average total cost per megawatt-hour over its lifetime (known as Levelised Cost of Energy – LCOE), which is still high, even if compared with fixed-foundation offshore wind . This high cost is what has hampered its use at large scales so far. Currently, there is 113 MW of floating wind in operation in Europe, spread across a few pilot plants. This is expected to rise to over 300 MW within the next two years (2024), including the 88 MW Hywind Tampen in Norway, aimed to supply power to offshore oil rigs.
Overview of Floating Wind Farms¶
The Challenge of Storm Events for Floating Offshore Wind Farms¶
Wind farm energy production soars during stormy events1, but due to special control systems embedded in wind turbine generators, designed to protect them from excessive structural stress, the power output of a WT reduces drastically, say, from 5-10 MW (also known as rated power) to zero. For FOWTs, high wind speeds trigger really harsh sea states so that wind–wave-control systems coupling effects are essential to understanding the individual power output2 (DNV 2021). This reflects badly on the stability of the total power output, and this would not be conducive to the grid resilience either.
Storms develop above the oceans and move inland to coastal areas, carrying high-speed winds and harsh ocean sea states; the length of the event is quite relevant and so to ensure power stability and security of the electricity supply, the power management system should be able to mobilize/activate storage facilities to make up for the power fluctuations that extreme weather events may trigger.
References¶
- Lauria 2024: Lauria, A., Loprieno, P., Francone, A., Leone, E., & Tomasicchio, G. R. (2024). Recent advances in understanding the dynamic characterization of floating offshore wind turbines. Ocean Engineering, 307, 118189. https://doi.org/10.1016/j.oceaneng.2024.118189
- DNV 2021: DNV. (2021). DNV-ST-0119: Floating wind turbine structures. Det Norske Veritas.