Ice Shedding and Ice Throw – Risk and Mitigation
GE Energy|David Wahl and Philippe Giguere|March 9, 2006
Wind turbines can accumulate ice under certain atmospheric conditions, such as ambient temperatures near freezing (0°C) combined with high relative humidity, freezing rain, or sleet. Since weather conditions may then cause this ice to be shed, there are safety concerns that must be considered during project development and operation. The intent of this paper is to share knowledge and recommendations in order to mitigate risk
Wind turbines can accumulate ice under certain atmospheric conditions, such as ambient temperatures near freezing (0°C) combined with high relative humidity, freezing rain, or sleet. Since weather conditions may then cause this ice to be shed, there are safety concerns that must be considered during project development and operation. The intent of this paper is to share knowledge and recommendations in order to mitigate risk
The Risk
The accumulation of ice is highly dependent on local weather conditions and the turbine’s operational state.[2,4] Any ice that is accumulated may be shed from the turbine due to both gravity and the mechanical forces of the rotating blades. An increase in ambient temperature, wind, or solar radiation may cause sheets or fragments of ice to loosen and fall, making the area directly under the rotor subject to the greatest risks[1]. In addition, rotating turbine blades may propel ice fragments some distance from the turbine— up to several hundred meters if conditions are right.[1,2,3] Falling ice may cause damage to structures and vehicles, and injury to site personnel and the general public, unless adequate measures are put in place for protection.
References
The following are informative papers that address the topic of wind turbine icing and safety. These papers are created and maintained by other public and private organizations. GE does not control or guarantee the accuracy, relevance, timeliness, or completeness of this outside information. Further, the order of the references is not
intended to reflect their importance, nor is it intended to endorse any views expressed or products or services offered by the authors of the references.
[1] Wind Turbine Icing and Public Safety – a Quantifiable Risk?: Colin Morgan and Ervin Bossanyi of Garrad Hassan, 1996.
[2] Assessment of Safety Risks Arising From Wind Turbine Icing: Colin Morgan and Ervin Bossanyi of Garrad Hassan, and Henry Seifert of DEWI, 1998.
[3] Risk Analysis of Ice Throw From Wind Turbines: Henry Seifert, Annette Westerhellweg, and Jürgen Kröning of DEWI, 2003.
[4] State-of-the-Art of Wind Energy in Cold Climates: produced by the International Energy Agency, IEA, 2003.
[5] On-Site Cold Climate Problems: Michael Durstewitz, Institut fur Solare Energieversorgungstechnik e.V. (ISET), 2003.
[6] Wind Energy Production in Cold Climate: Tammelin, Cavaliere, Holttinen, Hannele, Morgan, Seifert, and Säntti, 1997.
