A single turbine's position could dramatically reduce a wind farm's impact on avian life

By Jason Deign in Barcelona

Critical to any wind farm approval is the environmental assessment: a time-honoured process to ensure wildlife, and particularly birds, will not be affected by turbines. This is one the cornerstones of the industry’s green credentials. But what if the whole thing is wrong?

A new study by the Spanish National Research Council (Consejo Superior de Investigaciones Científicas or CSIC, in Spanish) suggests this may be the case. But do not panic: the findings could actually lead to more wind farms being permitted, not less.

Wind energy developers in the Cadiz province of Spain funded the research after becoming concerned by the levels of avian mortality in projects that had already passed a scrupulous environmental assessment as part of the permitting process.

“The Spanish regulations require all wind farms to undergo environmental studies,” explains Dr Miguel Ferrer Baena of CSIC’s Doñana Biological Station, who led the investigation.

“There are very similar precautions in Europe and the United States, and in Cadiz they were followed to the letter.” As a result, he adds, only 20 out of 53 original wind farm applications in the area got a green light. But once they entered operation, these 20 farms killed lots of birds regardless.

Individual turbine layout is key

Ferrer’s study uncovered a flaw in one of the main tenets of the environmental assessment process: that a greater density of birdlife will equate to a great kill rate on a wind farm. Instead, “it’s to do with how the wind moves as a function of the natural orography,” he says.

Essentially, in order to save energy birds tend to follow specific routes, like aerial highways, to get from A to B. Put a turbine in the middle of the highway and a lot of birds are going to get killed, regardless of how many turbines are nearby or where they are sited.

This explains why some farms harbour ‘killers’, or turbines that register unduly high avian mortality rates. And it has two important implications for wind energy developers.

One is that the traditional method of assessing wildlife on a wind farm, by carrying out a survey of the types and density of birdlife, is potentially useless in terms of calculating bird mortality.

Instead of treating the wind farm as a single entity, says Ferrer, surveys should focus on the sites chosen for individual turbines and see if they coincide with flight paths.

This could be done with little extra effort during the surveying phase, but could have a dramatic impact on the deadliness of wind farms. Ferrer calculates that eradicating the killers from a site would reduce the total energy output by as little as 0.07% while cutting bird strikes by 65%.

The second implication is that, provided flight paths are avoided, wind farms could be sited with little harm to wildlife in many areas that would fail current environment impact surveys.

That is good news for wind farm developers, and Ferrer is already working on models to predict likely avian flight corridors based on wind patterns and terrain contours.

Legislative lag

It may be some time, however, before his findings translate into policies that will benefit the industry across Europe and elsewhere.

Nick Medic, head of communications at the British wind industry body RenewableUK, says: “You could have difficulty in how research in one country translates into legislation in another.”

He points to turbine interference with radar, which is seen as a major issue for the industry in the UK but does not seem to have elicited much concern in the rest of Europe, despite no lack of radars or turbines.

At the same time, he notes, any failure to implement improvements to the environmental impact assessment process is unlikely to be a result of lethargy on the part of the wind sector.

“A lot of people are proud of the environmental credentials we’ve worked to build up so I don’t think you’ll find arguing for a slackening of standards,” he says. This, precisely, may be a problem for the wider acceptance of Ferrer’s findings.

The fact that the findings apparently favour wind farm developers may make it more difficult for governments to change current legislation, says Emerging Energy Research Europe wind energy advisory analyst Marc Mühlenbach.

“It’s easier if the effect is negative,” he points out. “The government can step in with a moratorium or impose a ban.”

This happened recently in Germany with harbour porpoises, when the alleged impact of underwater noise pollution from offshore wind farm developments prompted authorities to impose a ban on construction between May and August.

Mühlenbach believes it could take policy makers anything up to three years to work out whether Ferrer’s findings should be translated into a new environmental impact methodology. If Ferrer is right, though, then the wait could be fatal for many birds on the highway to a killer.

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Or write to the editor: Rikki Stancich