Sheringham Shoal goes offshore

On June 24 the first of 90 monopile foundations was installed off the Norfolk coast by the heavy lift vessel “Svanen”.

Over the next nine months, the vessel will install the remaining 89 foundations ready for the mounting of two substations and 88 wind turbines.

The wind farm will provide enough electricity to power 220,000 British homes.

Project manager in Statoil, Elly Kristine Bjerknes, is delighted to have reached a new milestone.

“On land, we’re already well ahead, the substation is nearing its final form, and the onshore cable is nearly finished. Now that offshore installation is getting underway, this is a big day for us,” she says.

Substantial dimensions

A monopile foundation consists of a tubular steel monopile, driven 32-36 metres into the seabed, and weighing from 400 to 600 tonnes. A transition piece is fitted to the top, forming the support for the turbine tower itself. Each piece is 22m high and weighs about 200 tonnes.

Installation of a submarine export cable is scheduled to begin in August, and submarine infield cables that connect the turbines and substations together in an intricate matrix on the seabed will start in October.

“Sheringham Shoal is a pioneering project for Statoil, since it’s our first wind farm,” says Bjerknes. “We are a small but effective team working on this, and we have had excellent help and support from other sectors of the organization. We really feel that we’re crossing energy frontiers,” she says.

Rapid progress

Project Director Rune Rønvik says that this is a major milestone marking the culmination of many years’ planning.

“The licence for the wind farm site was granted in 2004 and so it’s a great achievement to now be at the stage where we are starting a continuous process to install the 90 required foundations,” he said.

The Sheringham Shoal Offshore Wind Farm is owned equally by Statoil and Statkraft through the joint venture company Scira Offshore Energy Limited. Statoil is the operator for the project during the development phase. Scira will be the operator of the wind farm.

Facts about Sheringham Shoal 315 MW of installed capacity Located off the coast of Norfolk, England Covers an area of approximately 35 km2 88 wind turbines, each with a capacity of 3.6 MW, will supply clean energy equivalent to 220,000 homes  Turbine blade length 52 metres (170 feet) Turbine tower height 80 metres (262 feet) Wind turbines are placed on foundations on the seabed Two offshore substations Two 132 kV marine cables to come ashore at Weybourne 21.6 km underground cable will connect the wind farm to the National grid at a new substation