Wind-farm planners cannot afford surprises like the one that recently confronted Siemens. Just a few months before work was due to start on building the Sylwin1 converter platform off the coast of Sylt, a German island in the North Sea, the company had to completely revise its installation plan. A new survey of the seabed at the planned site had found that the subsurface contains a layer of soft silt, which means that the platform will need to be anchored much more deeply into the seabed than was originally planned. This is expected to delay the platform’s start-up by about a year. Previous analyses had failed to detect the silt problem. “If the fist survey had been more thorough, all this hassle could probably have been avoided,” says Florian Meier of the Fraunhofer Institute for Wind Energy and Energy System Technology IWES in Bremerhaven, northern Germany. Working with experts at the University of Bremen, Meier and his research team have developed a new surveying method that creates a detailed three-dimensional image of the structure of the seabed. He says that the system can get down as far as 200 metres and analyse the entire area of a future wind-farm site. The data can then be used to select the best location for the turbines – and because the data are so reliable, there is no danger of stumbling upon unexpected obstacles further down the line.
Whether it’s from waves, wind or water currents, any force that acts on a structure at sea ultimately gets channelled into the seabed. The composition of the seabed is therefore crucial to the stability of a turbine, and planners should know as much about it as possible before engineers finalise the design for the foundations.
This is an abridged version of the article – the full text is available in new energy issue 06/2013.
You can subscribe here or buy single issues of new energy: