The Danish Vendeby offshore wind farm is the world's first offshore wind farm. It was developed by Denmark's DONG Energy. It started operation in 1991 and was decommissioned and dismantled in 2017. Its life span was extended by 6 years than expected, providing electricity to 2,200 households. .
The Vendeby offshore wind farm is 1.5 to 3km offshore, with a water depth of 2.1 to 5m. It has 11 450kW offshore wind turbine generator units with a total capacity of 4.95MW, installed in Denmark. Near Vendeby (a small village in Denmark), as shown below, generate 20% more electricity than similar wind turbines on land.
The wind turbine foundation adopts a gravity foundation with a concrete caisson (caisson) placed on a gravel pad. The caisson is composed of a 14m diameter, 60cm thick plate, a 10m diameter cylinder and a cone, with a total weight between 710 tons and 1105 tons.
The main steps are as follows:
? The crawler hydraulic excavator placed on the barge completes the laying of gravel mat
? The concrete caisson was constructed at a nearby shipyard and transported to the site via a catamaran flat barge
? After the caisson is in place, Fill in sand and gravel and pour concrete around the base plate.
The 11 units of the Vendeby offshore wind farm are supplied by Bonus Energi (currently Siemens Wind Power). The impeller diameter is 35m and the tower height is 35m. They are transported and hoisted as a whole.
The main steps of installation are as follows:
? Transport the main components to the Nakskov Shipyard and assemble the wind turbine on the dock
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? The wind turbine is then loaded onto a transport vessel which sails to the wind farm
? The wind turbine is installed via a crane.
After more than 25 years of operation (in 2017), DONG Energy decided to dismantle the Vindeby offshore wind farm.
The mobile crane on the outrigger ship removes the blades, nacelle and tower in sequence. The concrete foundation was removed using hydraulic demolition scissors.
All components and foundations will be sent to Nyborg Harbor, where one unit will become an exhibit at the Danish Energy Museum.