Wind turbines can also cause actual bodily harm, both to humans and wildlife, in areas around installation sites. From a distance, the blades seem to move slowly but the tip speed on these turbines can approach 200 miles per hour, creating deadly obstacles for birds. Birds of prey are particularly vulnerable since they hunt in open plains where visibility is high. One particularly highly publicized wind farm, Altamont Pass in California, has been a lightning rod of controversy because of the impact poor planning has had on the bird population. According to the Center for Biological Diversity, as many as 1,300 eagles, falcons, hawks and other predatory species are killed each year because the wind turbines were constructed along a critical migration route.
People are also at risk. As with any developing technology, progress and understanding usually happen simultaneously. Blade throw, although it's rare these days thanks to design improvements, is a malfunction that occurs when a blade breaks free of the turbine and becomes a very large, very dangerous projectile. Similarly, wind farms that operate in cold climates are also susceptible to ice formation. Accumulating ice can fall or be thrown from turbines, potentially endangering surrounding people and property.
There are also more subtle health risks of wind farming. In her book, "Wind Turbine Syndrome: A Report on a Natural Experiment," Dr. Nina Pierpont describes a condition called "wind turbine syndrome" in which wind farms pose actual health risks to nearby residents. The sub-sonic noise generated by turbines is believed to cause maladies ranging from headaches and sleeplessness to dizziness and even depression. And visually, the flicker effect of spinning turbines can cause vertigo and even seizures.
For all its promise, wind energy is not without its own set of risks that should be weighed against the benefits. After all, it wasn't that long ago that petroleum was hailed as a cleaner, more efficient alternative to coal and helped power the world through the industrial revolution.