DHI Group has announced that it is implementing an innovative solution to reduce the scour of erosion protection systems at the Kriegers Flak offshore wind farm, whose developer is Vattenfall. The investment will reduce these costs by 30 percent.
Vattenfall needed a solution to reduce investment costs at the Kriegers Flak wind farm, located in the Danish part of the Baltic Sea. When fully operational, the wind farm will generate 604 MW of power, spread over 72 wind turbines. Kriegers Flak is by far the largest offshore wind farm in Denmark and has increased Danish wind energy production by about 16 percent. We wrote about the official opening of the wind farm HERE.
One of the most prominent threats to offshore wind farm foundations is scour caused by wave and current action, which can significantly affect the overall load on wind turbines. Currently, protection against foundation scour for wind turbines accounts for a significant part of installation costs. Vattenfall appointed DHI and LIC Engineering to design and optimize the erosion protection system for Kriegers Flak.
Developers protect foundations from water
The presence of a monopole in the marine environment alters the flow pattern of waters in its immediate vicinity, resulting in increased local sediment transport. This causes seabed scour around the monopile – a serious risk that can compromise the stability of the wind turbine foundation. In addition, cables on the seabed may be exposed to bottom erosion around the monopile. The foundation must therefore include relatively expensive leaching protection.
To keep the seabed around the monopile foundations at a constant level, the project used an erosion protection system consisting of rocks. Spill protection systems include the installation of a filter layer around the base of the monopiles, consisting of finer material and a reinforcing layer on top of the filter material.
However, a significant cost reduction could be achieved if only one layer of graded flood protection had to be installed – which this innovative solution proved to do. The wide-grained rock material acts as both filter and reinforcement and can be installed on site in one step.
Source: DHI Group