Dong Energy Completes Wind Turbine Installation at Walney 2 (UK)

In the night of 22 September, the last blade on the last wind turbine at Walney 2 was fastened.

However, it took waiting until the installation vessel, Kraken, succeeded in finding the weather window which made it possible to install the last blade on the last wind turbine in the wind farm. Now, all 51 wind turbines of Walney 2 are installed.

The blade was installed just five months and thirteen days after the first foundation was driven into the seabed, and together with Walney 1, Walney 2 is the world’s largest offshore wind farm with a total capacity of 367MW.

After the successful installation, the installation vessel, Kraken, demobilised and left the area.

 New benchmarks for the construction of wind farms

Besides being the world’s largest offshore wind farm, Walney Offshore Windfarms are setting new benchmarks for the construction of wind farms.

 Multi-contract principle

Walney Offshore Windfarms have been constructed according to the multi-contract principle which means that all project-controlling and construction settlement are managed by the project organisation. With some 348 direct supplier contracts, the project organisation has been in full control of all elements in the installation processes, and the multi-contract principle enables instant mitigation should any delay or faulty deliveries occur.

The close cooperation with the contractors and suppliers makes it possible to conduct a risk hedging based on the project’s interests and make a total priority of the resources.

 Optimised installation

At the same time, the project optimised the installation time through parallel installation. The installation of Walney 1 was planned to take one year, whereas the installation of Walney 2 was planned to be effected in half the time. Through parallel installation activity, the focus has been to utilise the favorable weather windows of the summer season. And through tight planning and logistics, it was possible to install Walney 2 in only six months.

Now it’s time for commissioning

Installation of the wind turbines is an important milestone in the project, but there is still some work left until all the turbines of Walney 2 are in operation. Intense efforts are made to commission the wind turbines, and the first production from the wind turbines are expected in near future. The entire wind farm is expected to be in operation at the turn of the year.

The cable installation vessel, Stemat 82, has loaded the last array cables from the Port of Barrow. Offshore work has been affected by poor weather. So far, 36 array cables have been installed, and one British Telecom cable crossing made. The British Telecom cable secures the connection from the main land to the Isle of Man.

In the design of the Walney Offshore Windfarm 2 layout a corridor for the British Telecom cable is included, and the cable will only be crossed by array cables in two instances in order to enable future repair of the cable, should any need occur.

 Armour layer

When all cables are laid, the turbine positions will be armoured with a layer of rocks for scour protection placed around the turbines in a radius of 15 meters around the foundation. The first loads of armour stones are expected to arrive at the construction site in November.

At Walney 1, the installation of the armour layer was postponed due to a fire in late February 2011 on the vessel, Pompei, as she was in port for repair works, leaving 16 positions waiting. Now these positions will be dealt with together with the 51 new positions in Walney 2.

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Source: dongenergy, October 20, 2011