Here is a reprint of an email about ice throw at Green Mountain Power's Searsburg wind energy facility in Searsburg Vermont. The email was written by John Zimmerman to an American Wind Energy Association listserv in 2000. Mr. Zimmerman managed the development of the Searsburg facility

Professor Terry Matilsky, associate professor of physics and astronomy at Rutgers University, addresses the kinetics of ice throw.

Dr, Kenneth Jaffe's response to the health and safety content of a June 2006 presentation by the NY State Department of State (DOS) in Delware County, NY.

The DOS presentation, which included a discussion of the impact of industrial turbine projects on communities and individuals, is intended to guide local officials in the process of writing regulations. Dr. Jaffe's response addresses what he believes are substantive misstatements, mischaracterizations, biased emphasis and faulty data contained in the DOS presentation.

During a recent roundtable discussion concerning wind power projects at the Delaware County Historical Society a participant affiliated with two local wind development companies stated that there were three issues where the health and safety impacts were predictable and avoidable---- ice throws, noise, and flicker. Since the statement was made in the presence of planners who are advising towns in the process of writing regulations to protect the health and safety of residents, I felt that a fuller discussion of the known science of these issues was important, and have prepared this report to that end.

Editor's Note: Dr. Jaffe's presentation to the Town of Meredith Planning Board on the proposed industrial wind plant vis-a-vis Meredith's 'vision' is available via the link below.

Editor's note: This short document prepared by personnel at the Wind Application Engineering Group of GE Energy provides some insight into the risks of ice throw. The content of this document confirms that ice fragments can be thrown large distances from the turbines.

This short GE Energy document explains the risk of ice build-up on the turbines and any mitigation. Note, the document acknowledges the risk of ice-shedding as well as ice-throw. An excerpt is included below. The full document can be accessed by clicking on the link.

"Today, the task before the Joint Committee (regarding Bill S40) is to hear from the public on what would appear simple

- the giving and taking of “driveway” easements between the Commonwealth’s Wachusett Reservation (Stagecoach Trail) and the Town of Princeton’s legal “right of way” for its wind power site. As well, the town is offering the to transfer to the Commonwealth, ownership of, five acres of their 16-acre wind site.

I urge the Joint Committee for Bill S40 to carefully consider the following with regard to your recommendations an for easement exchange and accession of land from Princeton:

1. The Wachusett Wind Site is a 16 acre parcel wholly surrounded by the Wachusett Reservation and flanked within few feet, on three sides, by the well traveled Midstate, Harrington and Stagecoach trails. This portion of the state park is accessible and popular.

2. The present eight windmills are 120-feet high and are proposed to be replaced with two windmills as high as a 35- story building and with blades that stretch as wide as a football field - windmills whose elevation will come with 150- feet of the mountain’s elevation.

3. In the wintertime Wachusett experiences unusual ice storms in number and severity

4. In the wintertime, the windmills accumulate ice - then release it when it melts and falls, when it is blown off by wind or is thrown it off by the rotating blades

5. This ice has put holes in the roofs of utilty buildings on the wind farm and scattters itself across the fully accesssible wind site, the state reservation and hiking trails, threatening state park viisitors The risk associated with being struck windmill ice can be quantified and is relative to one’s distance from the windmills and will increase geometrically with the proposed windmills.

6. Windmills and wind data collection towers at Wachusett have structurally failed five times in twenty years on the Town of Princeton (PMLD) site. This also threatens the state park visitors as well with collapsing metal structures and flying blades. Proposed windmills and data towers will not be installed in compliance withthe manufacuturer’s recommendations and safety warnings."......

BBC Research & Consulting's 2005 report for the National Wind Coordinating Committee that studies 9 wind plant sitings in an effort to identify circumstances that distinguish welcomed projects from projects that were not accepted by communities.

Dr. Terry Matilsky, Associate Professor of physics and astronomy at Rutgers University, addresses ice throws on behalf of the Kingdom Commons Group's opposition to the proposed East Haven Windfarm.

Ice throw is a concern related to the fact that any object at the end of the rotating blades is traveling at a high rate of speed. In the case of a 60 meter turbine (about 200’ diameter), rotating at 20 RPM, the tip of the blade is traveling at just over 140 mph. If the turbine diameter increases to 80 meters, the tip speed increases to just over 187 mph. There are reports of ice having accumulated at the tip of the turbine and upon breaking loose, traveling significant distance......