Germany reaps rewards of wind power maintenance

GERMANY: The economic case against running wind turbines into the ground has yet to be fully appreciated, and not everywhere sees the true value of a good maintenance regime.

German engineers are sought after worldwide
German engineers are sought after worldwide

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"What we see in emerging markets is that operation, management and inspection aspects are often underestimated," says Gerhard Gerdes, managing director of German wind turbine consultancy Deutsche Windguard.

In Germany this is not the case.

"Today, every single wind turbine in Germany is inspected by independent experts on commissioning, at end-of-warranty and at periodical safety inspections every four years," explains Gerdes.

"In addition, insurance companies demand condition-focused inspections every two years." This would check vibrations, and items such as gearbox bearings and teeth, bearings in general and rotor blades.

This kind of maintenance is still unusual in countries like the US and China, where operators or developers tend to rely on the manufacturing company for the commissioning inspection.

Developing skills

Ten years ago, the German wind industry realised that the country’s existing apprenticeship programmes did not match the demands of a growing industry.

Major players including Vestas, GE, Nordex and Repower joined forces to set up a non-profitmaking association, BZEE, to provide a platform to develop the skills needed.

German’s strong vocational training tradition meant that there was already a large pool of technically trained personnel who required only wind energy specific skills to fill the gap.

This gave the country a head start, and today its operations and maintenance expertise is being sought across the world.

BZEE is training partner for the German wind energy association BWE, and is now setting up training facilities in the US, France and Canada, including a teacher-training programme and the provision of technical training equipment.

The training is not a standard product, but bespoke. Each country is shown how to set up its own training infrastructure, which is the key to its success, says strategic adviser Gerald McGovern.

McGovern believes the importance of operations and maintenance (O&M) has been underestimated historically.

"From a supply chain perspective, O&M is quite low in the hierarchy. Yet, while the production and commissioning of a turbine takes about six months, O&M should cover its whole life span and is therefore decisive for delivering returns and making profits."

REETEC is a German wind energy service company with 15 years’ experience in on site maintenance.

In February, EDF Energies Nouvelles, the renewables arm of French utility EDF acquired 44% of REETEC shares to add to the 28% stake it already owned.

German technicians were initially sent to France, says Guillaume Bouchet, REETEC’s assistant for market development. But less than four years after the first shares purchase, REETEC now employs about 30 French technicians and only two Germans in France.

Learn by doing

REETEC’s method is for technicians to "learn by doing", Bouchet says.

German technicians encourage their French counterparts to keep their eyes open for things that are not in the manufacturer’s maintenance manual and to be proactive instead of solving a problem after it arises.

Bouchet says: "We aim to signal problems to customers before they occur. We do on site troubleshooting and repairs."

This would seem to strike a balance between the short-term appeal of a policy of little maintenance, with low initial costs but potentially high risks of expensive failures, and an over-rigorous regime, which could be costly and have only marginal incremental benefits.

Another aspect of O&M in which Germany leads is condition monitoring systems (CMS), which use sensors to spot changes in various mechanics of the turbine through vibration or oil condition.

German insurance firms have insisted on CMS for nearly ten years.

"Operators have realised that CMS is a good tool to predict failures on drive trains, plan maintenance, and analyse the toothing of a gearbox," says Bernd Höring, condition monitoring expert at German wind industry consultants 8.2 Consulting. "

Planned maintenance means planned costs, as opposed to unscheduled breakdowns, which are much more expensive."

Sophisticated analysis

The principles of condition monitoring are not new, but it is the increasingly sophisticated interpretation and analysis of the measured data that is making a difference.

8.2 Consulting has developed software that can analyse different CMS data.

The software is already used by turbine design company Windtec and in Sinovel’s offshore wind farm in China.

Höring says: "I am absolutely sure that CMS will be used everywhere in the near future. It is going to be standard for onshore 3MW turbines.

For offshore it’s already compulsory if the turbine is certificated by technical assurance and consulting company Germanischer Lloyd.

"So companies with CMS expertise will play a major role in Europe and worldwide, too."

While data is important, it is only as good those who interpret it. It takes years of experience to recognise whether a turbine needs to be stopped straight away or not.

Such decisions can be worth thousands of euros so the continued evolution of skills is vital.

Germany has shown that its O&M expertise can be applied around the world and it is eager to maintain its position as the leading authority in a fast-changing industry.    

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