Giant wind turbines ‘the future of UK wind energy’

The first giant offshore wind turbine, named Britannia, will be complete by 2012. It will tower 574ft (175m) above the North Sea, with blades that sweep a circle more than 100ft (30m) wider than the diameter of the London landmark.

Clipper chose the UK as the base for its wind energy project because of its proximity to the large European market for wind power and is sinking $65m (£44m) into building facilities, including a blade factory in Newcastle, and will use a new offshore wind turbine testing facility at the National Renewable Energy Technology Centre (NaREC) in Blyth.

Dubbed Project Britannia, the project is also receiving £5m from the local Regional Development Agency, One NorthEast.

Lead engineer Bill Grainger thinks future wind turbines will be even bigger, saying: "There isn’t a technical issue that screams out size limit." Offshore wind turbines are commonly capable of generating either 2.5 or five megawatts of wind power, but the Britannia will produce 10 megawatts.

That translates into enough electricity to power about 10,000 homes, and replace some two million barrels of oil during its lifetime.

Mr Grainger thinks Britannia is only the start of a trend towards a new generation of giant wind turbines, producing more wind power, more cost-effectively.

He told The Engineer magazine: "There might be a limit to the size that people want to put into the field; if a 20 megawatt wind turbine failed, that’s a big chunk of electricity to lose.

"But then, if a wind farm goes off-line you’ve lost 300 megawatts, so I don’t think that’s a limit either. "They’ll get bigger than 10 megawatts, is my feeling. How much bigger? I don’t know."

Mr Grainger is engineering manager at Clipper Windpower Marine, the UK arm of the US company in charge of the £44m Britannia build. Each of its blades will be 236ft (72m) long and will weigh more than 30 tonnes.

It is the enormous stress placed on these metal structures as they rotate that presents one of the biggest engineering challenges to increased turbine size.

Mr Grainger said: "You have to make changes as you get bigger. "Blades get floppier, for example, so you have to put more carbon in, but we aren’t anywhere near 100% carbon yet."

Britannia is being built at Blyth, in Northumberland, and is most likely to be placed on Dogger Bank, off the north-east coast of England.

Clipper Wind is one of two companies developing 10 MW wind turbines. The other is Norwegian firm Sway, based in Bergen, which has won a NKr137m (£14.5m) award from Enova, a Norwegian government body dedicated to funding and promoting wind energy technologies.

Both companies are at the design stage, but hope to have full-sized prototypes ready to deploy within the next two years. However, the two projects are taking very different tacks.

Clipper Wind, working from a base in Blyth, Northumberland, is looking at a conventionally styled wind turbine, 145m in diameter, with a solid foundation on the seabed, whose rotors face the wind head-on.

Sway, however, is developing floating wind turbines, anchored by a single flexible tether, which have their backs to the wind. Moreover, while the Clipper Wind version will have a geared wind turbine, Sway is developing a gearless direct-drive generator, using technology similar to that currently being developed by Enercon, Siemens and GE.