Safe setbacks: How far should wind turbines be from homes?

Let’s start with what one manufacturer considers to be safe for its workers. The safety regulations for the Vestas V90, with a 300-ft rotor span and a total height of 410 feet, tell operators and technicians to stay 1,300 feet from an operating turbine — over 3 times its total height — unless absolutely necessary.

That already is a much greater distance than many regulations currently require as a minimum distance between wind turbines and homes, and it is concerned only with safety, not with noise or visual intrusion.

In February 2008, a 10-year-old Vestas turbine with a total height of less than 200 feet broke apart in a storm. Large pieces of the blades flew as far as 500 meters (1,640 feet).

The Fuhrländer turbine planned for Barrington, R.I., is 328 feet tall with a rotor diameter of 77 meters, or just over 250 feet (sweeping more than an acre of vertical air space). According to one news report, the manufacturer recommends a setback of 1,500 feet, over 4.5 times the total height. In Wisconsin, where towns can regulate utility zoning for health and safety concerns, ordinances generally specify a setback of one-half mile (2,640 ft) to residences and workplaces.

But that may just be enough to protect the turbines from each other, not to adequately protect the peace and health of neighbors.

When part of an array, turbines should be at least 10 rotor diameters apart to avoid turbulence from each other. In the case of the proposed 77-meter rotor span in Barrington, that would be 770 meters, or 2,525 feet. For the Gamesa G87, that’s 2,850 feet; for the Vestas V90, 2,950 feet — well over half a mile.

Jane and Julian Davis, whose home is 930 m (3,050 ft) from the Deeping St. Nicholas wind energy facility in England, have been forced by the noise to rent another place in which to sleep. In July 2008 they were granted a 14% council tax reduction in recognition of their loss. It appears in this case that the combination of several turbines creates a manifold greater disturbance.

Since the human ear (not to mention the sensory systems of other animals or the internal organs of bats, which, it is now emerging, are crushed by the air pressure) is more sensitive than a giant industrial machine, doubling that would be a reasonable precaution (at least for the human neighbors — it still doesn’t help wildlife).

Sound experts Rick James and George Kamperman recommend a 1 km (3,280 ft) distance in rural areas.

Both the French Academy of Medicine and the U.K. Noise Association recommend a minimum of one mile (or 1.5 km) between giant wind turbines and homes. Trempealeau County in Wisconsin implemented such a setback. National Wind Watch likewise advocates a minimum one-mile setback.

More at Kirby Mountain

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One Response to “Safe setbacks: How far should wind turbines be from homes?”

  1. Bruce Varner Says:

    Thank you for the article. Is it possible to ask who the writer is?

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