Wind power has come into its own in Britain over the past few years. As the government has focused on it as a way to generate renewable energy, more and more windfarms have been built, onshore and offshore. It is fair to say that seeing the spinning blades on a wind turbine, in the countryside or at sea, has become commonplace. But in 2012 the capital will see a major development take the limelight, and it’s not the Olympics. It will be the biggest addition to the UK’s windfarms – the London Array.
Located on the doorstep of the capital city, by the Thames Estuary, mainly because of its high wind speeds and nearby ports to enable construction and maintenance, the London Array will, under optimum conditions, be Britain’s first 1,000MW windfarm. Owned by a consortium of three leading renewable energy companies – Dong Energy, E.On and Masdar – it aims to play a major role in enabling the UK to achieve its CO2 reduction and renewable energy targets. These include the aim of 15% of energy coming from renewables by 2020.
But, with so many windfarms being developed all over the world, what makes the London Array stand out? Well, basically, it’s all about size. It will be the world’s largest offshore windfarm, spanning an area of up to 200km2. Phase one will involve installing 175 turbines, two offshore substations and an onshore substation. These will generate a total of up to 630MW, with each turbine having an individual capacity of 3.6MW. Phase one will cost €2.2 billion to manufacture and install and should be complete by the end of 2012. Phase two depends on a satisfactory outcome to further bird studies. If all goes well, it should go ahead shortly after phase one has been completed to build yet more turbines to take the windfarm’s capacity up to 1,000MW.
So how will the London Array work? In a nutshell, electricity generated from the wind turbines will be taken through array cables, buried in the seabed, to the offshore substations. Export cables from the substations will bring the electricity to the shore. These cables run underground to an onshore substation where the electricity will be fed straight into the National Grid high-voltage network.
Richard Rigg, the London Array project director, has been on the project since July 2000. He says one main benefit of the windfarm is its location close to the major centres of London and South East England and that it will provide renewable energy for London. This will be a great benefit for Britain as South East England has the UK’s highest electricity demand.
“One main benefit I see is having such a large windfarm so close to the capital and identified with the capital,” he says.
Constructing the windfarm has really got going this year, with the first of 177 foundations – 175 for the turbines being supplied by Siemens, and two for the offshore substations – installed early last month. Installation will be a big challenge for the engineering and construction team, with a series of deadlines running through the next two years until the windfarm is handed over to the operations and maintenance team in early 2013. This will involve the remaining foundations being installed throughout the year, with the offshore substations, the first two of four export cables, and the array cables being installed from July onwards this year. In November, the installation of the wind turbines begins, and next year the remaining cables to connect to the substations will be installed.
The four export cables, which are being produced in Norway by engineering firm Nexans, are 53km long and are the heaviest items on the windfarm, weighing 4,600 tonnes each. Rigg says installing the export and array cables will be one of the most challenging parts of constructing the windfarm. He says that it is a job that tends to cause the most problems when installing a windfarm. With the London Array, a major issue is that the Thames Estuary has a series of shipwrecks and unexploded bombs in the seabed that could cause problems when installing the cables. Rigg says that, because of such hazards, the team has surveyed the area very carefully before the cables are laid and will re-route them where necessary.
Once shipped to Britain, all parts that make up each wind turbine – monopiles, transition pieces, foundations, turbine towers, nacelles and blades – will be put on to two installation vessels – the six-legged MPI Adventure self-propelled installation vessel and the Sea Worker, a straight jack-up vessel. These vessels are crucial to the project, as they work together to install the foundations and turbines. Between three and six turbines will be taken out on the vessels together. One at a time, each turbine tower will be erected using cranes and equipment on the vessels. They will be positioned 600m apart in rows, with rows 1,000m apart from one another.
The nacelles will then be placed on top, before the blades are fitted. Subject to weather conditions, the team expects to install one turbine every two days.
Getting the turbine foundations into position on the seabed will rely on a computer process called digital positioning. This is also used to position the export and array cables. The important thing isn’t necessarily to make sure that the turbines are equal distances from one another, but to make sure they avoid hazards on the seabed, within the limits prescribed by the consents. They must also not be put too close together because this can affect the seabed and the sediment that flows from it, which may cause the turbines to move in the water.
Rigg says: “A lot of work goes into the refinement of precisely where you are going to put each turbine foundation.”
Rigg says it is important that the engineering and construction team does as much of the construction work as possible onshore because it can be difficult working at sea. Work at sea can be delayed when the weather is bad. The two offshore substations, which weigh about 1,400 tonnes each, are, for instance, being fabricated and fitted out onshore in Belgium, before being lifted onto a barge and floated out to their locations.
“What you want is to make sure you have completed as much as you can onshore and don’t have to do the work offshore,” says Rigg. “The more you can do onshore the better. Everything you try and do offshore, you have to get the right weather. Sometimes you can be prevented for some time from getting access because you can only get up to the substations and turbines in certain weather states and wave heights.”
Once it is up and running, good maintenance of the windfarm will be crucial to make sure it lasts at least two decades. There will be regular inspections of the turbines to make sure they are in good condition and working to their full potential. In the meantime, the engineering team is trying to make maintenance as easy as possible, by building an operation and maintenance facility at Ramsgate, the closest deepwater port to the windfarm. Operation and maintenance will be based at Ramsgate throughout the life of the project and will allow the maintenance team to get access to spare parts, if, for example, parts of a turbine need repairing or replacing.
Rigg says: “What we are talking about is something that should last at least 20 years. Anything that happens in the very early stage of life of a turbine will have an effect on its overall reliability. If you can avoid one additional breakdown it will make a significant difference.”
There will be numerous challenges right through the supply chain and installation of the London Array. But one that has stood out, before any construction work started, was a shortage of UK companies to supply parts for the windfarm. Rigg says that UK suppliers at first did not jump at the chance to get involved in the project. He says that a lot of the manufacturing skills could have been transferred from shipbuilding and the oil and gas sector into wind power.
“The disappointment is that UK companies did not move earlier to pick up what really was quite a good opportunity,” he says. “There are a lot of skills that could have been passed across for fabrication activities associated with the foundations, for instance. All of that could have been done in the UK, but to date there really hasn’t been that much enthusiasm. But things are improving – things are starting to move.”
The London Array hasn’t been without its problems and Rigg says that it has taken a lot longer than he hoped to get to the current construction stage of the project. The windfarm was originally planned to be finished last year, but the objection of Swale Borough Council to the onshore substation and the subsequent public inquiry, plus additional delay to the grid connection when Shell pulled out of the project in 2008, delayed the project by two years. Now, however, with the new deadlines set, Rigg says construction is running to schedule.
“We are back on programme, which is great news, but it has been quite a battle,” he says.
Rigg has an impressive background in the power generation industry and has worked with the development of windfarms before. But he has never been involved in the construction of an offshore windfarm. So it is not really surprising that he is excited to be helping to lead what is being described as the UK’s flagship wind power project.
“We’re 10 years down the line and we’re just starting to install,” he says. “I have to say I’m absolutely delighted to still be associated with it and I hope to be able to see at least phase one through to completion and full operation.”
For and against the London Array
FOR – Peter Madigan
Peter Madigan is the head of offshore wind for the organisation Renewables UK.
He says the flagship windfarm is symbolic of the growth that the UK is seeing in offshore wind. This is helping to start more renewable projects, which is helping Britain to reach its carbon emissions targets. He says that wind is something that Britain is never short of – it does not need to be imported, nor does it create any waste, unlike other forms of energy.
Madigan says: “We need to rely less on coal and gas for electricity. So that is helping us fight climate change and helping us deliver our climate change objective.
“One of the things about wind energy is that it’s based in the UK,” he adds. “We own our wind. We don’t have to import oil, or gas, or coal or anything else to supply that electricity. And it doesn’t generate any waste at the end.”
In addition to this, Madigan says that windfarms are good for helping the economy, providing jobs for engineers and contract opportunities for big and small companies alike.
He says that while people may have concerns over cost, particularly with offshore wind, these will go down as wind technology progresses.
“Offshore wind is a new technology and with that comes new opportunities to create a supply chain,” he says. “We’ve seen that happening as well with companies investing in new manufacturing facilities and creating new jobs.
“As the new technology develops and grows, we will see costs coming down,” he says. “We are seeing a lot of innovation being driven in new technology, that’s not just new turbines, but also new foundations and new installation methods.”
AGAINST – Derek Birkett
Ex-engineer Derek Birkett is a writer and the former grid control engineer of Northern Scotland. He is a wind-power sceptic, has written books that show his disapproval of renewable energy, and is very much against the construction of the London Array windfarm.
Birkett says the main problem with windfarms is that they don’t produce enough energy, are unreliable, expensive and uneconomic.
“Windfarms, particularly offshore windfarms, are very uneconomic,” he says. “The whole thing is uneconomic from top to bottom.”
Birkett says he isn’t just concerned with how much it costs to build a windfarm, but how much it costs to maintain and operate it. There is also the fact that transmission costs are high and the wind is never constant, which means there has to be a back-up of power available on the national grid system.
“The whole business of energy is cost,” he says. “It’s all good in theory to have power coming from a windfarm, but it’s when you look at all the other items, all adding onto the cost, then you have something of a significant problem.”
He says the Dutch have shown that they aren’t cheering on the world of windfarms quite as much as the rest of the world, after Shell pulled out of the London Array. And Birkett believes that other countries may soon follow in its footsteps.
So what is Birkett’s solution? Not just to use an alternative to wind power, but an alternative to renewables altogether and a form of energy that goes back to basics – cleaner coal technologies.
“This is my argument: Forget renewables. Full stop,” he says.