Below is an excerpt of the minutes from the public hearing when ice shed was discussed:
Mr. Ciampitti asked about ice-shed and interference. Mr. Bashaw said that under very specific conditions, the blades could collect glazed ice. In certain cases, the turbine may be shut down. He said they may also have a heater on it to prevent ice from forming. Mr. Bashaw said that pieces may come off in rare cases, maybe 1-2 nights or zero nights per year. He said that other turbines have tried using an ice sensor similar to ones aircraft use. Mr. Richey noted that it was a long way from the rail trail and if the ice did shed it would be directly below, on the Richey property. They provided a clear area around the site for that purpose. Atty. Mead said ice would not travel 319 feet to the rail trail. Mr. Ciampitti asked what the impact of ice would be to the sound. Mr. Bashaw said it would be insignificant because blades will lose lift. He added that ice would drop below within about 50-75’ to the base.
Wind turbine manufacturers disagree. According to GE Energy's Wind Application Engineering Group "wind energy production in cold climate provides the following formula for calculating a safe distance: 1.5 * (hub height + rotor diameter)". Based on this formula, the proposed turbine could fling ice 560-feet away, well into the area of the rail trail and traffic on Route 1. This e-mail characterizing ice-shed at the Searsburg, Vermont wind facility provides some insight into the problem. (Note: the turbines at Searsburg are 100-feet shorter than that planned for Newburyport)