Spain is ripe terrain for this. As a pioneer in utility-scale wind power, thousands of megawatts are now approaching — some even surpassing — the 20-year mark.
At a March seminar dedicated entirely to extending useful wind plant life, Spanish turbine manufacturer Gamesa revealed its life extension (LE) service, with which it soon aims to offer full guarantees to extend life from the 20-year standard to up to 30 years while promising up to 98% turbine availability.
"Contracts are already negotiated," Sergio Velez, Gamesa life extension programme director, told Windpower Monthly at the event, held within the European Wind Energy Association (EWEA) conference in Barcelona, Spain, last month. Ideally, Velez believes LE should start around the 15-year mark, in time for major preventions.
Gamesa seems to be at the forefront of what is "a natural path for OEMs [original equipment manufacturers]," said Ruiz de Gordejuela of engineering start-up Nabla Wind Power, an independent LE provider — albeit without full guarantees — also at EWEA-Barcelona. Gamesa expects to attain certification for its LE service this year from GL-DNV, in order to provide solid guarantees for life extension and turbine availability.
The LE is based on Gamesa's real-life experience servicing more than 20GW of installed capacity worldwide. Other keys are a full plant audit, together with computer modelling and turbine condition monitoring to predict corrosions, wear and tear, fatigue and failures. "Knowing exactly where and when problems arise is essential," said Velez.
So far, life extension — as yet without full guarantees — is already available for Gamesa's 660kW machine. The company is also preparing an LE product for its 850kW and 2MW models.
Wind financers bank on a 20-year useful turbine life. Squeezing out an additonal five to ten years was once considered a bonus. But life extension is now essential for many Spanish companies to avoid negative results, said de Gordejuela.
That is because the right-wing Popular Party (PP) governing party is ending all subsidies for capacity online before 2005 — breaking the state's promise to maintain them for 20 years.
As an independent service provider, Nabla admits that it does not have access to the OEM's aero-elastic turbine mode. But, as "a company made up of turbine designers from across the sector," it has devised its own aero-elastic computer models for all major turbines, said de Gordejuela.
The company also works with clients to factor in a wind plant's track record. Furthermore, local partner Barlovento brings its wind measuring engineering expertise to LE modelling.
Contracting LE, at a cost of roughly 20-30% the initial plant investment, 50% extra life is attained, says Velez: "hugely cheaper than repowering". It is also an interesting option in Germany, where height restrictions prevent repowering with large new machines, according to one German delegate.