United Kingdom

United Kingdom

Offshore - huge logistical challenges facing contractors behind London array

UK: The success or failure of offshore wind projects depends on robust cabling and foundations. Yet contracts for these key technologies often receive fewer headlines than turbine deals.

One man who is keen to explain the magnitude and complexity of cabling projects is Ian Gaitch, director of Global Marine Systems (GMS), which recently won the contract to install cabling for London Array, the world's first 1GW wind farm, sited 20km from the Kent and Essex coasts between two sandbanks.

The installation of four export cables and the burial of 175 array cables represents a huge challenge, says Gaitch, as does the need to negotiate interchangeable conditions both above and below sea level.

"One of the biggest logistical challenges is getting all the right equipment in the right place at the right time," Gaitch says. The project is a complex jigsaw puzzle. Scores of conversations need to be held, a number of deals struck, and everything has to fit together. "Because of the number of subcontractors involved ... everything has to be in line," says Gaitch.

The sheer size of the project also presents GMS with a logisitical challenge.

"It is a vast area of seabed," says Gaitch. "The conditions can be difficult and cover many square miles in which we'll find all types of seabed. One issue is London clay, which is very hard to bury cables in. But in other areas there will be soft sand and uneven seabed."

Much of London Array's cabling will run in depths of 15 metres, but the turbines are sited in only 4-5 metres of water.

The work here is largely done on the surface and is at the whim of a change in conditions. "You have to be careful using barges and keep an eye on the weather," says Gaitch. Any withdrawal needs to be considered in advance. If the bad weather reaches the area before the barge has withdrawn it can cause problems.

With London Array and the £100bn Round Three development through the Crown Estate, the UK is ploughing billions into developing its offshore capability. However, despite this, GMS is one of the few British companies to be involved. Indeed, Gaitch says that for companies such as his own, there are better prospects overseas.

"There are a number of companies in the UK that can do offshore. But it seems to be the best opportunities are in Europe," he says. "If you look at Bremerhaven, Germany they are putting a lot of money into the ability to build wind farms there."

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