United States

United States

Program predicts bird kills

Care in siting wind generation facilities is the first step in cutting the number of collisions between turbines and birds, but developers of a new computer modelling tool say it can help developers fine-tune turbine placement and offer a way to show people how turbines will impact the bird population.

A new avian collision model, developed by Richard Podolsky of Texas-based Perot Systems Corp, allows developers to determine the risk of avian collisions based on turbine technology, bird species and the number, location and spacing of turbines in a plant. Podolsky has an academic background in both ornithology and computer science.

"If the project is designed properly and the developer does everything according to best practices for wind projects, then the potential to impact birds is minimised," he says, pointing out that a properly sited project averages two collisions per turbine each year.

Once the site is chosen, Podolsky says a developer can put the parameters of the project into the avian collision risk model, watch how birds will fly through turbines, determine the risk of collisions and determine, "How does this design influence birds?"

The results of computer modelling, which he has done for six wind projects under development, could help regulators to better understand the risk of the project to birds, but the modelling may better be used to convince the local public that a project is relatively harmless. "As wind power grows in the marketplace and more wind projects are installed, each new project will get a new set of constituents that need to understand wind generation," Podolsky says. "They will worry about noise and about their viewshed, and then they will worry about birds. This model brings developers, proponents and opponents together to understand how wind affects those birds."

Technical improvements have cut the number of bird kills per turbine far below what had earlier occurred at some areas of Altamont Pass in California. Early wind technology and poor siting resulted in the deaths of 30 to 70 golden eagles every year (Windpower Monthly, February 2003), for a time tarnishing the entire wind industry. With advances in technology, the Audubon Society, a national bird protection group, says it is no longer overly concerned with collisions.

"We favour wind power in general and view it as a good alternative energy resource," says the Audubon's John Bianchi. "It sometimes surprises people when we say we don't oppose wind, but the science just doesn't support that opposition." He says some of Audubon's local chapters will oppose individual projects if they believe them to be sited in areas where they would adversely impact native or migratory birds. "We want wind to succeed, but are very interested in siting issues," says Greg Butcher, Audubon's director of bird conservation. "We're more worried about offshore sites, such as at Nantucket."

He also pointed to critical areas where development may occur but should not, such as Hawk Ridge in Minnesota where a developer has erected several wind measurement towers. In addition, there is evidence that bird species in western grasslands, such as the greater prairie chicken, will not nest near turbines. Siting in those areas, he says, effectively cuts into the species habitat range. "We hope development stays out of these areas."

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