To the untrained eye wind turbines look the same as they did ten years ago. But they have been quietly getting bigger and better, and experts are predicting we could soon see turbines large enough for people to live inside

Despite the tightening credit conditions and well-reported spiraling cost of installing offshore wind power, those involved with wind energy industry have little concern over the future of the still fast exanding market.

They know that Obama’s renewable commitments in the US, and the EU’s targets, mean that the long-term demand is there regardless of any current financing difficulties. Moreover, they have seen the rapid pace of technological innovation that has characterised the sector over the past decade and are quietly confident that if turbine performance continues to imporve at its current pace it won’t be long until they no longer need subsidies to compete with fossil fuels on price.

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They have also seen what is happening in China, where total installed capacity has doubled every four years up to 2008, and where the state is in the process of installing a 3.85GW in one field on the edge of the Gobi desert– equivalent to the UK’s entire wind capacity.

“That project is gobsmacking, to use a technical term,” says Andrew Garrad, chief executive of Garrad Hassan, the largest wind consultancy in the world, adding that China is now fully committed to becoming a major manufacturing hub for the booming global wind turbine market.

Also gobsmacking are the technical developments going on inside the turbines.

Blades are much bigger than they used to be – the largest are now the equivalent of two end-to-end football pitches – and as a result turbines have to be significantly stronger to deal with the massive pressures imposed on the structure.

To make turbines stronger and minimize the risk of damage should they break, each blade on modern turbines now moves independently of the other blades, while high tech devices inside the turbine constantly measure loads on the blades and automatically adjust their calibrations in response to wind changes.

This makes them far more efficient that the dumb windmills of the 1980s and means they noty only deliver much higher energy outputs but should also last far longer.

But if so much progress has been made, why are developers reported to be reevaluating the business case for key projects such as the London Array?

The answer is simple. Installing wind capacity offshore is an entirely different game to doing it onshore, and currently about twice as expensive.

Whereas a company could reasonably expect to replace certain parts of an onshore turbine during its 15 year career, to do so at sea is prohibitively expensive. This is why some experts think turbines will have “keepers” in the future in the same way that lighthouses do.

In addition, more durable materials and methods must be used, knocking firms back down to the bottom of the learning curve.

But Garran thinks the high costs that have hampered offshore wind farm developers over the past year can’t get much worse. “We’ve currently at the peak,” he said. “Costs of offshore wind can only go down from here.”

Frank Mastiaux, chief executive of E.ON renewables agrees, though he says another step change will be needed from “offshore” installations to “farshore” installations in the middle of the sea. “There is a huge bottleneck in installation vessels, and they’ll need to improve as the offshore turbines get bigger – the nails on tripods for farshore turbines will weigh up to 100 tonnes each,” he said.

There are other problems, too. The entire internal workings of a turbine most be sealed and over-pressurised to prevent them being attacked by the corrosive salts of the sea.

E.ON is also looking at turbine designs for arctic conditions that must be as durable as far shore models, but also resistant to extreme cold and ice – it has already developed a 3MW prototype turbine for these conditions.

But these obstacles will be overcome, according to Mastiaux, and as subsidies are phased out market pressures will make companies even more innovative and progressive.

Ditlev Engel, chief executive of Vestas, adds that wind is the only renewable that will be recognised on a price par with oil and gas. “We have a head start in development yes, and the technology has developed fast, but wind is predictable, and increasingly cost competitive,” he argues.

And predictions that water will become an increasingly scarce commodity in the future also play in wind power’s favour – as unlike hydroelectric, geothermal and solar thermal developments it doesn’t need water to produce energy.

So where will the innovative development take us in the future?

Proposals for dirigibles – floating turbines in the upper atmosphere – will be welcomed by those who are fans of science fiction, but a rather more down-to-earth innovation may soon by helping manufacturers reach grid parity: selling advertising space on the shafts.

Top wind turbine designs

There are three main types of wind turbine – direct drive, gearbox and hybrid. Each has their advantages and disadvantages.

Gearbox

The original configuration – gears connect the low-speed shaft to the high-speed shaft and increase the rotational speeds from about 30 to 60 rotations per minute (rpm) to about 1,000 to 1,800 rpm, the rotational speed required by most generators to produce electricity.

Direct Drive

A relatively new technology where the turning turbines drive a generator directly. Used for offshore installations were maintenance is a big issue – changing a gearbox offshore costs the same as the gearbox itself. In July 2008, Siemens installed the first of two new 3.6MW direct drive turbines to assess whether direct drive technology is competitive with geared machines for large turbines.

Hybrid

An even newer technology being pioneered by Finnish companu Winwind, hybrid systems are, as you might expect, a middle route between gearbox solutions and direct drive solutions. Direct drive solutions often require more space, and Wiwind says hybrid systems “combine the reliability of a modern direct drive and the compactness of the traditional high speed gear system”.

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