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By LEE BOWMAN
Although thousands of giant windmills are generating power at wind farms in 36 states, a new government-sponsored environmental study says more attention needs to be paid to potential impacts on wildlife and humans as new complexes are built.
Commercial wind-generating capacity has quadrupled to more than 11,000 megawatts since 2000, enough to power more than 3 million average homes for a year. Yet wind turbines produce only about 1 percent of the nation’s electricity.
President Bush and other wind-energy advocates think it’s possible that wind energy could eventually meet up to 20 percent of the nation’s power needs. But the study from the National Research Council of the National Academies of Science assumes that wind’s share of the mix will increase to a maximum of 7 percent by 2020.
Even that much growth means that as many as 36,000 new windmills, each with blades equal to the wingspan of a 747 jet on towers up to 300 feet tall, would have to be built on high ground where the wind blows an average of 10 miles an hour or better.
The study, ordered by Congress, was intended to "be the most complete compilation of environmental impacts, and impacts on humans, positive and negative, from wind energy that’s yet been done," said Paul Risser, chairman of the committee that wrote the report and a researcher at the University of Oklahoma at Norman.
Aside from some reviews on the impact on migratory birds, federal regulation of wind projects on private land is minimal, the report observes. And while some states have developed guidelines, wind energy is such a recent addition to power production in most areas that most states are relatively inexperienced at planning and regulation, unlike a handful of states like Texas and California that have large concentrations of wind farms.
The good side of wind energy, of course, is that once in place, turbines don’t pollute air or water and the breeze is the ultimate renewable fuel. The report figures that if wind power does produce 7 percent of the nation’s energy by 2020, it would offset as much as 4.5 percent of emissions of greenhouse-gas carbon dioxide produced from electricity generation.
Windmills are not entirely benign. Birds and bats run into the blades and die, in some places in fairly large numbers but, "We don’t know the total population of many species, so we don’t know if we find 100 dead bats beneath a turbine if that’s 100 out of 10 million or 100 out of 100 million," Risser said.
While most wind farms have been set on large tracts of open land already used for agriculture or grazing, a growing number are being built or proposed for sites closer to resorts and vacation homes, even neighborhoods.
Some people living close to windmills complain that they’re too noisy, or that the twirling of the blades creates a strobelike effect that can make people dizzy or nauseous. More often, potential neighbors argue that the giant structures and the roads and power lines that support them ruin the landscape.
There are also unanswered questions about the effect the turbines’ electromagnetic fields might have on television, radio and cell-phone transmission, as well as navigation systems.
"We wanted to make a clear statement about the kinds of questions that need to be asked when making decisions about siting these projects," Risser said. "We’ve tried to lay the groundwork for a planning guide at various levels of government."
In some regions, particularly in New England and the Appalachian highlands of West Virginia, Virginia, Maryland and Pennsylvania, a number of wind-farm projects have been proposed that might have a regional impact on wildlife or recreation, yet are only being considered on a case-by-case basis, the committee said.
"There needs to be some way to compile the projects and consider their cumulative impact when considering where to place additional equipment or putting conditions on them, so that they can be systematically evaluated," Risser said.
On the Net: http://www.nationalacademies.org/nrc