Vindeby Offshore Wind Farm near Lolland in the south east of Denmark was constructed in 1991 as a demonstration project which was to prove whether it was possible to generate green power offshore. Now, the dismantling process has been completed.
The world's first offshore wind farm was a great success, but after more than 25 years of operation, the Vindeby wind turbines were worn down, and DONG Energy therefore decided to decommission the wind farm. In March 2017, contractors commenced the dismantling of the 11 wind turbines. Blades, nacelle and tower were dismantled and taken down individually by a mobile crane and placed on board a so-called jack-up vessel.
The concrete foundations were broken down on site, mainly by hydraulic demolition shears and a hydraulic hammer, but also by breaking down the concrete using milling tools. The broken-down concrete and reinforcement structures were subsequently collected.
The first dismantling of an offshore wind farm
"This is the first time we're dismantling an offshore wind farm, but luckily, we've been able to draw on our vast experience from constructing offshore wind farms and working offshore," says Leif Winther, Senior Lead Business Developer in DONG Energy. He continues: "In cooperation with the winning contractors, we developed the dismantling method and entered a long process with the authorities to obtain all necessary permits."
Throughout the dismantling process, up to 20 workers have taken part in the work, which took place in periods when the weather permitted offshore work. Water depths of only two to five metres added to the challenging conditions, as only a limited selection of vessels were able to work in the area.
All wind turbine components and parts from the foundations were shipped to shore in Nyborg Harbour. The components will be reused as much as possible as spare parts for other wind turbines, while the blades will be reused in an innovative noise barrier concept. Prior to this, however, some of the blades will become part of a research project at DTU Risø. Components that are not immediately reusable have been transported to a certified recovery company.
After having generated green power for more than 25 years, the traces of the world's first offshore wind farm, 'Vindeby' near Lolland, are now gone.
"And the tale of the world's first offshore wind farm off Vindeby on Lolland will be preserved for posterity with one wind turbine from Vindeby Offshore Wind Farm becoming part of the exhibition at the Danish Museum of Energy in Bjerringbro in Jutland," says Leif Winther.