Increase in annual energy production through passive self-adjusting layouts of floating wind farms

Abstract

Wind energy is essential for transitioning to sustainable energy sources. To harness its full potential, it is crucial to access locations with abundant wind resources. Interestingly, 60% to 80% of the most promising wind energy sites are located in deep waters offshore. These sites can only be utilized using offshore wind turbines. Harnessing wind energy in deep waters not only taps into rich wind resources but also aims to boost the efficiency of wind farms by reducing energy losses. A significant source of these losses is known as wake losses. The power generated by a wind turbine depends heavily on the wind speed hitting its rotor, specifically, it is proportional to the cube of this wind speed. As wind passes through a turbine, the blades extract energy, resulting in the wind flow, leaving the turbine with less energy, lower wind speed, and higher turbulence. When this lower-energy wind reaches another turbine downwind, the second turbine receives less wind speed and, therefore, produces less energy compared to the turbine upwind. This difference in energy production due to the shadowing effect of the first turbine is called wake losses. This research introduces a new method to reduce wake losses in floating wind farms. The approach involves passively relocating the floating offshore wind turbines to optimize their positions relative to each other. Unlike fixed turbines, floating offshore wind turbines are secured to the seabed with mooring lines, which allow them to move within a certain range. The extent of this movement depends on the design of the mooring system, as well as the wind speed and direction. For a given mooring system, the displacement of the turbine changes with varying wind conditions. Thus, by smartly designing the mooring system, we can control the movement of floating turbines to minimize wake losses. This study explores the concept of designing customized mooring systems to create a floating wind farm layout that can adjust itself passively and reduce wake losses. These self-adjusting layouts should not only reduce wake losses but also be cost-effective. The design must ensure that the new mooring systems' costs are lower than current state-of-the-art mooring systems. Additionally, the fatigue and extreme loads on the turbine components mustn't increase due to the larger displacements of the turbines. The research findings show that a passively self-adjusting wind farm layout increases a floating wind farm's annual energy production (AEP). Importantly, this improvement is accomplished without increasing the extreme and fatigue loads on the turbines, maintaining the safety and reliability of the FOWTs. For a layout of nine turbines, the AEP was increased by 1.5%, and the mooring system costs were decreased by 4%. For the Horns Rev 1 layout in the North Sea with 80 turbines, the AEP increased by 1%, and the costs decreased by 6%. These results indicate significant potential for scalable and cost-effective improvements in floating offshore wind energy production. In summary, this work presents a promising approach to enhancing the efficiency of floating wind farms by smartly designing mooring systems that allow turbines to adjust their positions passively. This innovation not only taps into abundant offshore wind resources but also enhances energy production and reduces costs, paving the way for more sustainable and efficient wind energy solutions.