Documents filed under Icing
This short paper prepared by Professor Terry Matilsky, Department of Physics and Astronomy at Rutgers University, explains how ice or other debris flung from a turbine blade can travel significant distances.
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......
3.8 Health & Safety Affected Environment, Environmental Impacts and Mitigation Measures "A number of comments submitted for the scoping process for the Desert Claim project EIS addressed concerns relating to potential health and safety issues. Specific topics indicated in these comments included certain possible hazards that are uniquely associated with wind turbines, such as blade throw and ice throw; health and safety issues associated with electrical and magnetic fields; more common hazards such as fire; and the incidence and impacts of shadow flicker, another phenomenon specific to wind turbines. Section 3.8 addresses these wide-ranging health and safety topics that have been identified as concerns for the environmental review. "
Catharine Lawton's letter to the attorney representing Addison Wind Energy on the developer's failure to represent accurately a number of the dangers associated with icing of the blades of industrial wind turbines.
This document prepared by Henry Seifert and others documents the risk of ice shed and ice throw on turbines operating in an area where ice can build up on the blades.
"This paper provides an overview of the issues affecting wind turbine operations in cold weather with a special emphasis given on atmospheric conditions prevailing in the Northeast United States. The first section describes previous and more recent wind energy projects in cold weather areas. In the second section, environmental elements most likely to impact on the operation of wind turbines in cold weather are introduced: low temperatures, icing and snow. It also presents various climatic situations and their specific behavior in cold weather. The third section suggests some solutions to problems identified in the previous section. In addition, this paper suggests ideas of further research on the operation of wind turbines in cold climate. It also identifies organizations interested by similar issues whose cooperation would be beneficial."
"Developers and owners of wind turbines have a duty to ensure the safety of the general public and their own staff. However, there are currently no guidelines for dealing with potential dangers arising from ice thrown off wind turbines. This puts developers, owners, planning authorities and insurers in a difficult position. To rectify this situation, the work presented here has commenced in order to produce an authoritative set of guidelines. Initial work has resulted in the development of a risk assessment methodology which has been used to demonstrate that the risk of being struck by ice thrown from a turbine is diminishingly small at distances greater than approximately 250 m from the turbine in a climate where moderate icing occurs."