Regulators in Vermont are seeking a sound limit on wind power projects that would be among the quietest in the country.
Renewable energy advocates say the rule regulators want is too restrictive and would effectively ban the development of wind power in Vermont. The move comes as the state moves forward with some of the most aggressive renewable energy goals in the nation.
"This rule will make most, if not all, large wind projects unworkable in Vermont, taking this critical clean-energy resource off the table," the Vermont Public Interest Research Group said.
The rule filed by the Vermont Public Service Board on Tuesday would set a 42-decibel sound restriction for turbines during the day and 39 at night. The standard is now an average of 45 decibels per an hour, quieter than a normal conversation.
The board's rule filed Tuesday also requires larger turbines to be set back 10 times their height from a residence, with a waiver available on a case-by-case basis.
The proposed rule now goes to a legislative committee for approval.
The nonprofit group Vermonters for a Clean Environment wanted an even lower sound level during the day and standards established for low-frequency sound.
"It could have been a lot better to be truly protective, but it is a great improvement over what has been in place for the operating big wind projects," said VCE founder Annette Smith.
The board had considered a sound standard of 35 decibels at night, and said it received well over 100 comments from people saying the level was too restrictive. It said it disagreed with commenters who argued the proposed lower sound limit would have effectively halted wind powered electric generation in Vermont.
Site selection will need to be more carefully considered, and the lower sound limits will reduce the number of options with sufficient wind but not eliminate them, the board said.
It added that wind developers could work more with neighbors and have the sound limits removed.
"If a developer engages with the neighbor of a proposed project early in the process, the developer may be able to take steps to reach agreement with that neighbor on becoming a participating landowner, thus removing the sound limits for that residence," the board wrote. "It is the Board's goal that more 'buy-in' from neighbors during the planning process will lead to projects with more support and less controversy."
The state has a long-term goal of getting 90 percent of the energy it needs from renewable sources by 2050.
Last year, Vermont's then-health commissioner told lawmakers that "no scientific research has been able to demonstrate a direct cause-and-effect link between living near wind turbines, the noise they emit, and physiological health effects."
Public health agencies in Canada and Australia commissioned studies that reached similar conclusions however Australia's National Health and Medical Research Council suggested more research could be done for those living closest to wind farms.
This story has been corrected to show that Vermont's proposed sound standard is among the quietest in the country.