Future wind turbines - inside Spain's National Renewable Energy Centre

SPAIN: From below, the small buildings and weather masts on top of the Alaiz mountain, in Spain's blustery northern region of Navarra, give little away as no wind turbines have yet been installed. But up there sits one of the biggest sources of collective pride for the Spanish wind industry: Europe's only public field-test facility for prototype super-size wind turbines. All infrastructure at the test site is now fully in place and ready to go.

Spain's prototype testing plant at the National Renewable Energy Centre

"We just need to clear final local-authority permits for turbine installation," says Pablo Ayesa, director of the wind energy department at Spain's National Renewable Energy Centre, Centro Nacional de Energias Renovables (Cener), owner and operator of the site. He expects the giant turbines to be turning and undergoing tests by the end of the year.

The new test plant is the EUR15 million planned extension of Cener's EUR50 million turbine test laboratory, Laboratorio de Ensayos de Aerogeneradores (Lea), which is located at the foot of the same mountain in the district of Sanguesa. Sanguesa is just 50 kilometres from the Navarra capital of Pamplona, where Cener has its headquarters and other renewables laboratories. The King of Spain, Juan Carlos I, inaugurated Lea in 2008 as the world's largest public wind turbine test facility. There, nacelles and blades are subjected to the forces they would experience in their useful lifetime, with performance monitored throughout. Testing is carried out on drive trains of 2-6MW and on blades of up to 100 metres.

Gurutz Urzelai, manager of Lea, acknowledges there are bigger existing private and partial facilities, some testing generators, others blades or gearboxes - such as gearbox manufacturer Hansen's 13GW test centre. But Lea is testing drive trains, generators, nacelles and blades "all under one roof; and we are doing it for any customer", Urzelai says. Before Lea, the world's only comprehensive test facility was at the US National Renewable Energy Laboratory (NREL), which tests drive trains up to 2MW and blades up to 50 metres. Cener is now transferring part of its experience as adviser on a new 15MW US drive-train test centre at Clemson University in South Carolina.

Science in the field

Back up the hill, the experimental plant is now at a pre-commercial stage, says Jose Javier Armendariz, director general of Cener. The facility has six positions for turbines of up to 6MW. "Within a month we expect to sign up a minimum of three positions and there appears to be immediate interest for signing up two more," claims Armendariz. "All major wind turbine manufacturers operating on Spanish soil have shown an interest."

Client confidentiality prevents Armendariz from naming names. The top manufacturers in Spain are: Gamesa, Vestas, Acciona, Alstom-Ecotecnia and GE Energy.

"The site has privileged conditions together with facilities not found at commercial wind farms," says Ayesa. It is swept by high-speed and high-density winds - class I winds in sector jargon - "the kind of wind usually found on much higher hills without the easy road access of Alaiz", he explains.

Lea has measured and calculated average annual winds at Alaiz to be enough for class I turbines to generate power equivalent to producing at full nameplate capacity for 3,000 hours. That represents a capacity factor of 34.3%, equivalent to a plant running at full nameplate capacity for about one in every three hours over a year.

Cener has installed five fully calibrated weather masts at different points. The plant also has three fully synchronised so-called lidar systems, which use a laser beam directed into the airflow to give accurate detail on approaching wind forces. In commercial operations, that helps turbines adjust rotor orientation (yaw) and blade angle (pitch) ahead of the forces acting on them - reducing wear and tear from the strain. Without lidar, turbines react once the force is acting on them. At a test site, lidar helps interpret a turbine's reaction to those forces under different electro-mechanical configurations. Three synchronised lidars at the Lea site give three-dimensional imaging of winds, as well as of the wake after passing through the turbine.

Above all, the plant will test complete prototype turbines, though Ayesa says it is also open to testing new systems and components in commercially tried-and-tested turbines, such as control systems, blades or converters. "But there must always be a major new technological element," he adds. However, given the investment involved in installing and monitoring a turbine, as well as leasing a position at Lea, Ayesa points out that testing a full-blown prototype is the most cost-effective way to use the facility.

Cener remains coy about the costs incurred by clients. Investment in the facility was EUR15 million and the centre has a stated aim of being as close to self-financing as possible to ease its burden on taxpayers.

As in most research-and-development (R&D) centres, that is achieved through technology transfer and leasing of facilities. So, as with the nacelle test centre, the experimental plant will receive income from leasing and services, although Cener declines to disclose rates. Last year the entire centre - including its wind, solar, biofuel and biomass activities - generated EUR10.4 million, enough to cover 84% of its expenditure for 2009.

Growing demand

Ayesa believes there will be plenty of ongoing demand for Lea and its new test plant. "In 2000, when Cener initiated conversations with NREL, it seemed nobody in Europe was interested in creating a turbine test facility," he says. "Nobody believed there would be enough demand to justify the costs; but look at us now, working at full pelt with order books full well into the future," he adds, referring to the drive train and blade test centre at the bottom of the hill.

"Two years ago, NREL was the only public turbine test facility to include full drive train testing," adds Ayesa, pointing out that it was rare for turbine manufacturers to test whole machines. But now Clemson University is building a 15MW drive train test facility to complement a new blade test facility in Massachusetts. Similarly, the UK is planning a super-size blade and drive train test facility.

"It simply makes economic sense to invest in testing," says Armendariz, back at Cener's headquarters in Pamplona. In Spain, the government has proposed doubling the 19GW of wind power already online over the next ten years.

"Wind has already reached considerable penetration levels," says Armendariz. In 2009, it covered 14.3% of annual demand, reaching momentary peaks of over 50%. "Further development is going to require a high degree of attention to detail to ensure optimum technological performance for the good of the electricity system, the wind power producer and the electricity consumer."

"Previously, the possibility of demanding thorough turbine testing simply didn't exist," continues Armendariz. "Banks were hard pressed to get guarantees on the reliability of the technology they were financing. But now we can offer those guarantees." Wind power is continually pushing to improve efficiency, cost cutting and grid integration. "That all requires new designs, which imply risks of the unknown," adds Ayesa. "The only way to reduce risk to the absolute minimum is by using a test facility."

"The bashing we give the drive train over six months is equivalent to what it will receive in the field over a 20-year lifespan," shouts Urzelai above the noise. As the turbines' essential equipment can be tested exhaustively, design faults can be identified and corrected before making the first series of turbines, which are, effectively, prototypes, Urzelai says. At Lea's main building, blades and generators all take a similar beating.

Up at the experimental plant, real-life performance is monitored, further reducing time-to-market of new designs, according to Armendariz. Apart from the R&D aspect, the site also acts as a showcase for demonstrating new technology to prospective clients, he adds.


As anybody visiting Lea will discover, security is tight. Once in the heart of the building, doors will only open for exit if visitors are accompanied by a Cener official. A trip to the fully automated lavatory involves being accompanied to the appropriate part of the building. Cener staff in Pamplona - often working on designs for turbine systems and components for industrial clients - are not allowed in the Lea building, apart from a few officials, including Ayesa and Armendariz.

Confidentiality is so strict that none of Cener's staff can say which clients have used the facility or what machines have been tested. They are not allowed even to confirm whether machines have included direct-drive, offshore or onshore. The only officially announced client is Gamesa. Gamesa's press office, which has not yet publicly announced work on a 5MW machine, says: "Lea plays an important role in Gamesa research and development and, in particular, in the design and development of our new high-power turbine in the 5MW range."

The only other insight offered by Armendariz is that four different drive trains have been tested since the end of 2008.

Despite the prospect of wind turbine designs going into double-digit megawatt figures - such as Sweden's 10MW Sway machine - Armendariz is not unduly worried about Lea's restriction to 6MW. The global onshore and offshore market still has to go through consolidation of the 3-6MW turbine range, he believes.

"Large-scale development using 10MW machines is still on the distant horizon," he says. In other words, Lea's work has only just begun.