Much-debated limits on turbine noise get lawmakers’ OK 

She said the Vermont sound limits – 39 decibels during the day, 42 at night, measured 100 feet from residences near wind turbines – will not prevent all further wind energy development.

The U.S. Energy Information Administration predicts wind power will be the cheapest form of new energy generation by 2022.

However, the overwhelming majority of Vermont’s energy comes from fossil fuels, followed by wood and dammed rivers, according to the state’s comprehensive energy plan, published last year.

As a result, Vermont is “nowhere near” achieving its renewable energy goals, and there’s very little currently in place to change that outlook, according to analysts in the Department of Environmental Conservation.

But these considerations were not before the committee Thursday.

With the committee’s mandate limited, debate instead centered on the PUC’s rationale for the proposed rules, and to a lesser extent on the views of some lawmakers who wrote last year’s legislation instructing the PUC to draft a set of uniform sound limits for future wind development.

The rationale was the same that gave rise to the sound limits the commission has applied to existing turbines, PUC staff attorney John Cotter told lawmakers Thursday.

In all its sound standards, the commission has intended that turbine noise shouldn’t exceed 30 decibels inside nearby homes, Cotter said.

That number comes from the World Health Organization, which has found that most people get a good night’s sleep when they’re not exposed to indoor noise louder than 30 decibels, averaged over an eight-hour period.

But basing sound standards on indoor readings is problematic, not least because it requires in-home monitoring that can be intrusive, critics say.

The commission tried to arrive at an outdoor sound limit, to avoid this problem, Cotter said.

It used research from the World Health Organization and others on noise reduction as sounds travel through the walls of a house, he said. Commission members arrived at the 39 decibel figure based on that research.

The daytime sound limit of 42 decibels came from current technical limitations of wind turbines, which often have a “noise-reduced operation” setting that quiets them by as much as 3 decibels, Cotter said. With this mode, turbines can produce as much as 42 decibels at nearby homes and power down to 39 decibels at night, he said.

The PUC’s rationale satisfied Sen. Joe Benning, R-Caledonia, that the limits weren’t arrived at arbitrarily.

Benning delivered a lengthy statement to that effect and cautioned his seven fellow committee members that they themselves might be acting arbitrarily if they disagreed.

He also read portions of a letter from Sen. Chris Bray, D-Addison, in which Bray said the sound limits uphold the intent of legislators who commissioned them. Bray is chairman of the Senate Natural Resources and Energy Committee, which wrote that bill.

Rep. Robin Chesnut-Tangerman, P-Middletown Springs, and Sen. Mark MacDonald, D-Orange, voted against the rules Thursday. Five other legislators voted in favor of them, and the remaining lawmaker on the rules committee, Sen. Virginia “Ginny” Lyons, D-Chittenden, was forced by scheduling conflicts to leave before the committee voted.