Environment: Wind farms not all they are cracked up to be

Environmentalists differ strongly about wind farms - the massive arrays of giant windmills driving turbines.

Some say that they should be built out of sight - and few would argue that hundreds, or for that matter a dozen, of them suit the landscape. For by design, they have to be where the wind is, and that often means the most beautiful desolated countryside of hilltops and high-wind valleys.

They are noisy, disturbing residents with the swoosh of their blades and the whine of their turbines and, until now, no full study had been made of their effect on wildlife.

A new study released yesterday suggests that not only do wind farms, particularly land based examples, cause harm to wildlife, they don't even have many of the touted benefits - at least not to the extent it is claimed.

Indeed, the US Academy of Science found "officials who will decide whether to build the turbines have few tools to measure the devices’ impact on air quality, on animals like birds and bats, and on wilderness preservation."

In short, the wind farms do not have the effect of reducing pollution - although it is accepted that as their power is fed into the grid, it will mean less power needs to be generated by more polluting means. But not by much: the report, which assesses environmental benefits and drawbacks, estimates that "by 2020, wind energy will offset about 4.5 percent of the CO2 that would otherwise be emitted by other electricity sources."

Worse: the committee concluded that use of wind energy to generate electricity probably would not significantly reduce emissions of two other pollutants, sulphur dioxide and nitrogen oxides, because current and expected regulations of these are largely based on cap-and-trade programs. The degree to which emissions would be further reduced through special provisions to encourage wind-energy use -- such as set-asides, in which a percentage of emissions allowed under the cap are retired to the extent they can be offset by wind energy -- is uncertain, the committee added.

The effect on wildlife is more uncertain: "Wind facilities can have certain adverse environmental effects on a local or regional level, by damaging habitat and killing birds and bats that fly into turbines. Among birds, the most frequent turbine fatalities are nocturnal, migrating songbirds, probably because of their abundance, the report says. However, the committee saw no evidence that fatalities from existing wind facilities are causing measurable changes in bird populations in the United States. A possible exception is deaths among birds of prey, such as eagles and hawks, near Altamont Pass, Calif. -- a facility with older, smaller turbines that appear more apt to kill such birds than newer turbines are." The report says that there is insufficient information to determine the effects on birds of wind farms out at sea.

Wind projects also can be disruptive because of noise and shadow flicker, a strobelike effect caused by rotating turbine blades, says the Report. The report recommends that noise surveys be conducted before a project is sited, and that processes be set up to respond to noise complaints. Shadow flicker has generally not been a problem at wind facilities in North America, the report says; new turbines can be located so that their shadow paths avoid residences, or operations can be halted during times when troublesome flicker occurs. That's fine in a big empty country: it's not the experience in many parts of the UK where wind farms are closer to settlements.

Read the full report online: National Acadamy of Sciences website

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