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A fair wind for London

Relying on the weather for our power is risky, but that risk is manageable

By Prospect Team  

Turbines in the London Array. © London Array

 

The world’s largest offshore wind farm stands in the Thames Estuary—the London Array—175 vast wind turbines rising out of the sea.

“Each turbine is 3.6 megawatts and has a rotor diameter of 120m, bigger than anything you would see onshore,” says Benj Sykes, Vice President UK Wind at Dong Energy, which builtLondon Array with its partners and now maintains the array.

“There is a total of 630mw of generation sitting out there in the Thames Estuary about 20kms offshore, producing enough electricity for almost half a million homes in the UK and cutting CO2 emissions by about 900,000 tonnes a year,” he says.

The turbines are located in a shallow part of the estuary, where the bases of the turbines can become exposed at very low spring tide. The deepest waters in which the array stands are no more than 25m. The UK is blessed with a coastline that includes a large amount of shallow waters, which, Sykes points out, makes Britain especially well suited to the installation of offshore wind turbines.

“One of the things that Dong Energy is very focused on is reducing the cost of electricity from offshore wind,” says Sykes. “And picking really good sites that have really good wind resource but also stand in relatively shallow waters is a very important part of that drive to reduce costs and to reduce the demand on consumers.”

The wind farm is operated out of Ramsgate, in Kent, where London Array has its operations base. The array is owned jointly by a consortium including E.ON, Masdar and CDPQ, the Canadian pension fund.

The wind farm is supported under the Renewables Obligations scheme, which is the government’s main support mechanism for renewable energy in the UK. Under the terms of the scheme, there is support for the energy produced by the array, though no backing was provided for its construction.

The turbines, being so new, are efficient with very high levels of availability—meaning that power flows from the windfarm most of the time.

“They are designed to be out there for twenty-plus years,” says Sykes. “We have wind farms around the north west Europe offshore wind market that have been around for considerably more than ten years.” The London Array is expected to remain fully operational for at least that long.

There are plans to create more wind farms on the scale of the London Array. Dong, with its partner Scottish Power Renewables, recently completed a project 15km off the Cumbrian coast, consisting of 108 turbines of a similar size to those in the London array. Electricity started to flow last year, after the wind farm was opened by Ed Davey, the Secretary of State for Energy and Climate Change.

Dong is currently building a further wind farm off the cost of Yorkshire.

“It is only 35 turbines,” says Sykes, of the Yorkshire project, “but they are bigger turbines than we have used before with a rotor of 154m. And that gives us another step towards reducing the cost of wind energy electricity.”

“We have said we are going to cut the cost of electricity from offshore wind by 30-40 per cent by the end of the decade,” he says. “Things like going to bigger turbines is a crucial part of that.”

“This makes the Yorkshire wind farm a very significant milestone not just for Dong, but for the industry as a whole,” says Sykes.

Just before Christmas, the company announced plans to extend a pre-existing wind farm off the coast of Liverpool. This will include the use of 8mw turbines, with 164m rotors.

When it comes to the contribution to Britain’s energy mix made by offshore wind farms, Sykes says that “we could be well above 20 per cent and considerably more than that—but it very much depends on our success in driving costs down.”

Having a large component of the national energy supply based on the weather inevitably brings some degree of uncertainty. But so long as wind energy accounts for below 30 per cent of Britain’s energy needs, says Sykes, then that uncertainty should remain easily manageable.

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