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Maximising life cycle cost -- Launch of a 3 MW turbine

When Spanish construction giant Acciona moved into the wind business with its purchase of Energía Hidroeléctrica de Navarra (EHN) in 2005 it inherited not only EHN's portfolio of operational wind plant and its wind project development business, but also a 1.5 MW turbine developed with the primary aim of learning more about wind turbine technology. Three years later, Acciona has applied all the gathered knowledge of the company as both a wind plant owner and turbine manufacturer into a new 3 MW machine, launched onto the market last month at the US wind industry's annual trade show.

Building a turbine from an owner's perspective brings a different approach than an original equipment manufacturer (OEM) that purely sells turbines, says Peter Duprey, Acciona's head of North American operations. "We just think differently, we think like an owner," he adds. "I've seen it from both sides," he continues, referring to his experience leading GE Energy's acquisition of both the wind plant and turbine manufacturing assets of Enron Wind and the maturation of those assets under GE as a pure a technology supplier.

"Acciona has been operating wind turbines for almost 15 years, and we started out as a developer and just buying other OEM's equipment and each turbine had its own issues," Duprey says. "So essentially we took those lessons learned and incorporated those into our own design."

Acciona's inclusion in the 3 MW unit of a dual main bearing, not common on other turbines, is a direct result of those lessons, though GE also employs what it calls "a double bearing main shaft" in its 2.5 MW turbine for the European market. Although doubling up adds more weight and more complexity, Acciona says the configuration does a better job of isolating and dampening rotor vibrations and preventing them from reaching the sensitive gearbox.

Acciona has also strived to improve conditions for maintenance technicians, providing a roomy nacelle for easier access to components, including direct access to the rotor. The result is a large nacelle resembling a torpedo-like aircraft fuselage. The turbine offers the largest rotor available for its generator size in North America, at up to 116 metres, much bigger than the 90 metre span on the Vestas 3 MW unit.

Concrete towers

Acciona's larger swept area requires the use of 100 or 120 metre towers, which are made from pre-stressed concrete rather than steel, a better economic solution for towers in that range, says the company's Adrian LaTrace, head of manufacturing in the US. He believes concrete towers will become more prevalent as turbines get bigger.

Adding technology refinements means adding to turbine cost, but that is not what is most important, says Duprey. "When I was at GE, we used to have debates over whether we put more things in the turbine that might raise the cost. And a lot of the time we found the developers weren't willing to pay for it. In part, I think, because the US market tended to be a build and flip market and they didn't have an owner-operator mentality. As an owner-operator, I want to maximise lifecycle cost, not turbine cost."

The broad base of Acciona's wind business means it can capture value at each part of the value chain, from manufacturing, through development, ownership and operations and maintenance, points out Duprey.

Acciona, which has factories in Spain and China, is now ramping up production at its fourth facility, in West Branch, Iowa, and intends to produce about 800 MW a year in the US between its 1.5 MW and 3 MW turbines. About 600 MW will go to Acciona's own projects. The exact mix between the two turbine models will be determined by market demand, says LaTrace. The company will accept orders for the larger machine in 2009 for deliveries in the second half of 2010.

As an owner, Acciona operates about 330 MW in North America, much of it in Canada. Last month it was commissioning its 180 MW Tatanka project, split into two 90 MW chunks in North and South Dakota. Including its EHN inheritance, Acciona has built 5300 MW of wind plant and operates about 3800 MW. It claims that tally ranks it second in the world behind Iberdrola, but Emerging Energy Research, an independent information provider, puts it in fourth place behind America's FPL Energy and Portugal's EDP.

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