When completed this summer, the record-breaking wind farm will be able to generate more than 70 per cent of Aberdeen’s domestic electricity demand
By: Phoebe Braithwaite
Wind turbines are getting bigger. Last week, the world’s most powerful wind turbine rose out of the sea off the coast of Aberdeen, Scotland. It’s the first of eleven such beasts which will make up the European Offshore Wind Deployment Centre, Scotland’s largest offshore wind facility. The remaining ten are expected to be installed and operational by the end of the summer.
Developed by Swedish state-owned company Vattenfall, and part-funded by the EU, the wind farm will cost £300 million to build and is hoped to be able to generate more than 70 per cent of Aberdeen’s domestic electricity demand, and 23 per cent of its total demand. A single propellor rotation can reportedly power an average home for a whole day.
The 8.4MW turbines are 191 metres high. For scale, this is over half the height of the Shard in London, which is the tallest building in Europe. The company overcame various challenges including a legal challenge from Donald Trump in constructing the first turbine – the US president objected to it on the basis it would be visible from his golf course.
“The average size of offshore wind turbines installed last year was 5.9MW but GE recently announced the development of a 12MW turbine, which is enormous,” says Andrew Canning from Brussels-based advocacy group Wind Europe. Larger turbines capture more energy from the wind because of larger rotors with higher megawattage and longer blades. Being taller is also handy as wind generally moves faster at higher altitudes. According to Vattenfall, the new turbine has a blade rotor diameter of 164m, a blade length of 80m and a tip height of 187m. The recently-unveiled Haliade Xfrom General Electric has a rotor diameter of 220m and a blade tip height of 260m.
This wind surge has involved a lot of innovation: in 2017 Norwegian firm Statoil built the world’s first floating wind farm also off the coast of Scotland. The £200m Hywind project uses an underwater ballast at a depth of 78m and three tethers attached to the seabed to keep the turbines moored.
“We can install turbines further out to sea than we could before, where the wind speeds are higher. They also open up new sea beds – such as the Mediterranean and Atlantic – which were too deep for traditional offshore wind,” says Canning of floating wind farms. Nine floating projects, with a total of 338MW of capacity, are on course for commission by 2021 off the coasts of France, the UK, Ireland and Portugal.
In an industry first, the Vattenfall plant uses “suction bucket foundations” to hold the turbines in place at a lower cost than traditional foundations: an upturned steel ‘bucket’ is lowered into the seabed, using a crafty engineering suction trick to create quicksand where it digs in. Lifting this giant sink plunger out slightly then creates a vacuum that roots it in place. An Asian Hercules III crane with lifting capacity of 5,000 tonnes was used to erect the turbine.
The turbines are also packed with sensors that monitor the weather and the performance of components. The Vattenfall project can also operate at lower wind speeds than normal, helping it generate electricity more of the time. “This is all helping to bring the cost of offshore wind down,” Canning says.
In 2017 alone, the UK built another 1.7GW of capacity – 53 per cent of total new installations across Europe. It is currently the world leader for installed offshore wind capacity. The continent as a whole saw a 25 per cent increase in capacity during the same time.
2017 was also the first year that more of Britain’s electricity came from renewable and nuclear sources than from gas and coal, with wind generating twice as much electricity as that generated by coal. According to Smith at the Carbon Trust, at present “over 25 per cent of our electricity is coming from wind alone, both onshore and offshore, according to data from Elexon”. This percentage is rising rapidly – in 2017, wind energy covered 15 per cent of electricity demand.
The broader picture is not so good. Last year it was reported that the UK is not likely to meet its 2020 target for 15 per cent of overall energy to come from renewable sources – though the EU as a whole is on track to reduce its reliance on fossil fuels by getting 20 per cent of its energy from renewables. But the UK has come a long way since 2005, when only 1.5 per cent of fuel was sustainable. Brexit could change the way future targets are met and perhaps the targets themselves, with ministers set to scrap the EU’s green energy targets upon exit, according to The Telegraph.
However, Steve Westlake, a spokesperson at the government-facing Committee on Climate Change (CCC), says that “the UK has legally binding targets that are independent of, and at least as challenging as, EU targets. The UK is therefore committed to moving to a low-carbon future regardless of Brexit”. The CCC confirms that “progress is stalling” when it comes to greenhouse gas emissions. “Since 2012, emissions reductions have been largely confined to the power sector, whilst emissions from transport and building stock are rising.”
For the government, offshore wind is crucial for its plans for a low carbon energy future. “With the effective end to the public support for onshore wind, offshore wind provides the only real large-scale renewable energy opportunity for the UK,” Smith argues.