By Sam Phipps in Edinburgh

Turbine reliability must step up a gear if wind power is to expand in line with ambitious targets.

Investment in European wind energy is on an upward curve but would be even higher if turbines were more reliable, analysts say.

Some €13bn (US$16.6bn; £10.8bn) were invested in the sector in 2009, according to the European Wind Energy Association, with €1.5bn (US$1.9bn; £1.2bn) of that going on offshore installation, and the organisation predicts both sums to rise again this year.

Some 10,000MW of wind capacity were installed across the EU last year, up 23% on 2008. Onshore capacity rose by 21% and offshore by 56%.

However, the relatively high failure rate of turbines is seen as braking growth in the sector as Europe aims to source 20% of electricity from renewables by 2020 – a dramatic scale-up compared with 8.5% today.

Too many new designs, too many unknown variables

One Dutch-led investigation, PROTEST (Procedures for Testing and Measuring wind energy systems), has found an average rate of between two to five turbine failures a year that need visits from technicians.

If that is costly and time-consuming onshore, it is significantly more so offshore, where turbines are increasingly popular because bigger turbines may be used because of a more reliable wind resource.

Jessica Holierhoek of the Energy Research Centre of the Netherlands (ECN), one of the partners in the PROTEST project, says that in the rush to produce frequent new designs – and in large quantities – manufacturers risk using inadequate components.

“There is no time to check whether the components are loaded beyond the design load limits or to improve the design procedures,” Holierhoek  says.

Previous studies have shown that the loads on mechanical components are not being calculated with enough accuracy, according to PROTEST, whereas the procedures for rotor blades and towers are much more specific because they are critical for safety.

“Most failures are seen in the electrical components and control systems but it’s the high cost of problems in the mechanical systems – the gearbox, drive train, pitch and yaw systems, for example – that causes the biggest financial burden.”

PROTEST’s other partners are Suzlon Energy GmbH, Germanischer Lloyd (GL), Hansen Transmissions International and the German Wind Energy Institute (DEWI), the University of Stuttgart and Greece’s Centre for Renewable Energy Sources.

Component quality standards reduce risk

The group’s two-and-a-half year study, using structural and aerodynamic models, has been part funded by the EU and is due to be published within the next few weeks. But Dr Holierhoek admits the most significant finding is that it is “probably not possible” to devise strict standards for all manufacturers because of the huge variety of wind turbines.

PROTEST is thus aiming to help raise the bar in terms of what can be expected in terms of component quality and suitability.

Michael Holm of Vestas agrees that potential investors are rightly focused on reliability but insists that maintenance can be efficiently priced into operational costs. Clients of the Danish wind turbine giant, with its long track record and proven technology, have no more to fear from gearbox wear and tear than a car owner going for a routine service, he says.

Issues of reliability and cost effectiveness have played a major part in Vestas’s decision to stick to gearbox transmission over direct drive, Holm adds, though the latter technology is being increasingly developed by several rivals including GE.

Vestas has also preferred to keep its turbines on the smaller side. “We could easily put a 10MW or even 15MW turbine to market but the question is: would it be cost efficient and reliable for customers?” Holm says.

“Investors don’t care if a turbine is pink or has one blade or three or four. They look at the business case and want to have the certainty that it will give a return. After the financial crisis, that’s even more the case.”

Reliability wins over investors

At the time of publication Vestas was due to host a two-day capital markets presentation in Colorado Springs for institutional investors, analysts and media, in order for company executives to highlight technological breakthroughs and pitch for greater investment in its turbines.

Michael Scheff, senior strategic supply chain manager at Mitsubishi Power System Europe Ltd in Hamburg, is equally adamant that reliability is uppermost in the minds of designers and engineers, and the ethos goes from OEMs right the way through to final delivery and maintenance.

“Reliability is an absolute need, and we do an extraordinary amount of testing to ensure we have no problems later on,” Scheff says. “We specify our needs [to OEMs] and from time to time we have to check various issues with them of course. It is natural to have to clarify points but our requirements always have to be fulfilled.”

As Holierhoek of ECN says: “High reliability of wind turbines and their components is one of the prerequisites for an economically viable exploitation of wind farms, especially for offshore. Therefore reliability needs to be increased.”

The industry appears to be of the same mind but questions remain over how it will deliver.

To respond to this article, please write to:

Sam Phipps: samcphipps@yahoo.co.uk

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Rikki Stancich: rstancich@gmail.com