The bird problem at the Tarifa wind farm in Spain has been studied and suggestions for solutions presented, including shutting down the worst offending wind turbines, using radar to detect flocks of migrating birds to enable temporarily shut down of the installation, and using a mini-glider to track the flight of birds.

A wind farm in southern Spain being built by Kenetech Windpower of California has been described by the company's own expert as being situated in "what is possibly the worst place in the whole of Western Europe for tangling with migrating birds." The site, a veritable Mecca for ornithologists, could also provide unwelcome publicity for the American company, says Colin Pennycuick of Bristol University's School of Biological Studies in England.

Kenetech's Bill Whalen ruefully admits that the report's worst case scenario reflects "a worse case nightmare for me." The company is already putting some of the British expert's recommendations into effect. It has relocated the projected siting of at least four of the turbines considered dangerous to birds and is looking at other solutions not reflected in the report, including the use of radar to detect incoming flocks of birds. This would enable operators to shut down wind turbines on problematic ridges. Whalen says project costs will increase as a result, but Kenetech had made an internal decision to "spend a lot of dollars in dealing with the avian issue throughout the world, wherever we are."

Pennycuick's three page report, Bird Problems At The Tarifa Wind Farm, partially reflects the views of the Spanish Ornithological Society/Birdlife International (SEO/BI) which has been trying to block further wind development there until a study it is carrying out is concluded early next year. The area is described by both Pennycuick and the SEO/BI as a "pinchpoint" or "bottleneck" for migrating soarers: white storks, many species of eagles and smaller raptors and immature griffon vultures, according to the report.

Pennycuick was hired by Kenetech in August to assess the avian mortality problem at existing and projected sites at Tarifa. Controversy has been raging for months about the impact of the wind farms on birds in the region. At least 50 birds, most of them griffon vultures, have been killed there over the past year and ornitholgists claim the wind farms could wreak havoc with one of the world's major migration routes. Kenetech developed a site in Tarifa in 1992 with Abengoa Wind Power (AWP) of Spain. This partnership was dissolved and Kenetech is proceeding with the new wind farm alone.

An instant fi

xSuccinct but surprisingly detailed, given the three days he was given to study the situation at Tarifa, Pennycuick's report includes biological data on the main victims -- the griffon vultures -- identifies the existing individual wind turbines most dangerous to the birds at Tarifa and proposes a number of solutions. The most radical of these is the removal of turbines, but he also suggests an instant fix for the 20 turbines on the Tarifa ridges which he considers to be the worst offenders. On the premise vultures do not hit stationary turbines, he proposes increasing the cut-in speed of the machines so they do not rotate in low winds when vultures cannot get the lift to fly over them. By requiring the turbines to cut-in at higher wind speeds, the lift would be sufficient to propel the birds over the blades, he says. Pennycuick also suggests using a mini-glider to track the flight of birds at Tarifa by simulating vulture aerobatics in the vicinity of the turbines -- a method he has used with success in Africa.

But his report centres mainly on Kenetech's new 30 MW project, split into two developments at locations called La Ahumada and El Cabrito. Here the company plans to install 30 MW, produced by 90 of its newly developed 33M-VS design. The development will virtually double the current wind output at Tarifa.

Pennycuick points out that in the middle of the more north-westerly La Ahumada site, a rocky outcrop serves as a vulture night roost. "Hundreds of vultures sometimes roost during the winter," he says, suggesting that it would be highly undesirable to put turbines there. The second group of turbines, to go in the ground to the southeast, "is situated in what is probably the worst place in the whole of Western Europe for tangling with migrating birds," he says, adding: "The interesting time will be next spring, when flocks of storks and raptors start coming in from Africa." He continues: "On the not so good soaring days they will come in over the beach at wave top height and then work their way up the slope to get better soaring conditions inland. The first obstacle is the ridge along which the new turbine string is going to be located. The birds will scrape low over the ridge, through the line of turbines."

The biologist, who was accompanied in Tarifa by Kenetech executive Michael Haas and Mark Fuller, a consultant with the company, envisages a lightning backlash from the many international bird watchers who flock to study birds on the ridge and could witness avian fatalities among the wind turbines. Pennycuick describes the development as a gamble for high stakes, "Combining as it does maximum potential for massacring birds with a highly public location." He goes on to suggest deploying local observers to keep an eye on bird movements once the turbines are erected, saying they could be shut down when flocks are expected during peak migration. He also believes the new Kenetech plant could act as a determining factor for further development of sites in Tarifa. "Perhaps the migrating flocks will fly unharmed through, around or over the lines of turbines," he says. "If that proves to be the case, then we can be reassured that problems are unlikely at other places."

In-flight information

Towards the end of his report, Pennycuick expresses surprise that preliminary research on bird migration was not carried out prior to the decision to build along the ridge and points out that an abundance of material exists. "We read about it during the flight to Gibraltar, in a feature article in the airline's in-flight magazine," he says, referring to his trip to Tarifa with the Kenetech team that accompanied him. He concludes that greater effort should be made in scanning bird literature before future sites are developed and local ornithologists consulted or recruited to help resolve the problems likely to arise. His last paragraph contains a warning for all wind power developers with their sights on Tarifa: "We may be sure that the same problem will occur in the area north of Tarifa, where wind farm expansion is contemplated."

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