Scour prediction and scour protections in offshore wind farms

Abstract

This paper is the result of research whose main objective is to analyse different methods used for the prediction of maximum scour depth and scour extension, and for the design of scour protections in offshore wind farms located in shallow water, using medium and large diameter monopile foundations. Physical agents such as waves, currents and wind play a major role in the design of structures like offshore farms. As a result, the study has highlighted the need for introducing experience backed climate monomials such as the dimensionless wave height parameter (Ho) and proposes the use of formulations that can express the extent of scour protections as a function of waves in transitional waters.

An investigation into the effect of scour on the natural frequency of an offshore wind turbine

“…This means that the natural frequency of the wind turbine structure could vary considerably as scour and backfilling occurs. It is also noteworthy that, in many cases, the actual scour depth occurring around a turbine foundation at a wind farm site may be less than the design value so there is still some uncertainty present in the prediction of an equilibrium scour depth (Matutano et al, 2013 The change in mode shape exhibited by the full wind turbine structure for the loose sand case is shown in Fig. 12.…”

“…Moreover, Matutano et al (2013) have compiled a list of different formulae used in the prediction of maximum scour depths which have been derived assuming different flow conditions (current-only, wave-only or combined current and waves). They have highlighted that different standards and recommendations used in the offshore industry suggest different formulations for scour depth estimation, leading to natural variability in design scour depths.…”

Improving wind farm accessibility for operation & maintenance through a co-located wave farm: Influence of layout and wave climate

“…The available resource, larger than in the case of onshore wind, has the potential to supply larger quantities of renewable energy [2], and in this manner harvest wind energy more efficiently. However, offshore installations involve a greater Operation & Maintenance (O&M) demand due to the harsh marine environment, which translates into higher costs and longer down-time periods [3]. In fact, O&M costs of offshore wind farms typically amount to between 20% and 25% of the total lifetime costs of the installation [4].…”

Sinking of concrete modules into a sandy seabed: A case study

“…Scouring is one of the threats to the foundational stability of both riverine and maritime structures. Although flow-induced scour around bridge piers has received significant attention for many years, wave-induced scour around marine structures has not become a topic of interest to researchers till the 1990's (Bricker et al, 2012;Matutano et al, 2013;Negro et al, 2014;Sumer and Fredsøe, 2002;Whitehouse, 1998). The presence of marine structures in a coastal flow regime changes the flow pattern in the immediate neighbourhood of the structures.…”