As offshore wind farms move into ever deeper water, developers are exploring alternatives to the traditional monopile foundation in order to reduce costs and keep the technology competitive within the energy marketplace. HR Wallingford is helping DONG Energy refine the design of one such alternative – the suction bucket foundation – as part of a research project to determine how these structures interact with, and impact upon, the hydrodynamic conditions and the seabed.
The action of waves and currents can lead to erosion of the seabed around wind turbine foundations. This phenomenon, known as scour, poses a risk to the stability of the foundation and, in extreme cases, has the potential to cause structural failure. Although scour is relatively well understood for traditional monopile foundations, the same is not currently true for complex foundation types.
Laser scanners measure the movement of sediment around a 1:32 model of a suction bucket foundation, helping HR Wallingford’s scientists to understand the potential impact of scour.
Prof Richard Whitehouse, HR Wallingford technical director said:
“The forces acting on offshore wind foundations will typically increase as water depth increases. For complex foundations, we currently use a combination of approaches to estimate likely scour, and this introduces a level of uncertainty in the design process. This research with DONG Energy will help us to develop greater certainty in the prediction of seabed response and design more efficient foundation solutions. Ultimately this will help to make offshore wind developments more costs effective, and developments in exposed locations and deeper waters more economically viable.”
Designs that have been shown to be reliable in the laboratory are likely to be adopted by developers as there is also a requirement for the technology to be proven before its application for use in large-scale developments.
Andreas Roulund, lead oceanographic engineer at DONG Energy Wind Power said:
“The ability to have novel designs tested by physical modeling is crucial for development of our foundations. We can observe how the seabed responds to the foundation in the extreme conditions found in the North Sea. We have found the new Fast Flow Facility at HR Wallingford tailor made for this purpose.”
Samantha Dawson, renewables business development manager at HR Wallingford said: “We are pleased to support DONG Energy on this important project to advance foundation design for their offshore assets. As a recognized leader in scour around marine structures, we are proud to offer our clients our next generation of physical modeling facilities. These uniquely provide a controlled environment for evaluating new and innovative scour protection systems for developers investigating novel foundation performance.”
Since launching the Fast Flow Facility at the end of 2014, HR Wallingford has been examining the complex interaction of waves, current and sediments at a larger scale and in more detail than was previously possible, helping clients to optimize designs more effectively and minimize project risks.