Why Ice Throw from Wind Turbines in Cold climates has become a Low Risk
The operation of wind turbines in a snowy/cold climate such as Canada’s involves additional challenges not present in warmer locations. Icing refers to any accumulation of ice or snow on a wind structure. Icing occurs when water that is present in the air freezes after it comes in contact with a surface. This can either occur within clouds (in-cloud icing) or result from precipitation (precipitation icing). In-cloud icing usually forms rime, while precipitation icing forms glaze, drizzle or wet snow. The International Energy Agency (IEA) has established a classification for icing climate sites according to meteorological icing, instrumental icing, and production losses. This classification provides a first sign on the severity of icing and its consequences for a potential site. You can find a map of Canada with the different classes of icing that also illustrates the distribution of icing severities across Canada. (Link)
The operation of wind turbines in a snow/cold climate such as Canada’s involves additional challenges not present in warmer locations.
What is Ice Throw?
When turbines have accumulated ice, it may throw ice if the blades are in motion. Ice throw is when ice detaches from the moving blades. Wind direction, wind speed, rotational speed and position and size of the ice fragments on the blade will influence the landing position of the projected ice pieces.
The maximum throwing distance for ice throw can be determined with the following empirical formula:
𝑑𝑡 = 1.5 ∗ (𝐷 + 𝐻)
dt = Maximum throwing distance (m)
D = Rotor diameter (m)
H = Hub height (m)
Naveco takes pride in supporting all phases, including the development, construction, and operation of all projects. This includes Naveco’s assurance that we fully consider all concerns of potential hazards and risks are fully, and we meet safety requirements.
Hazards and Risks
When a wind farm is being developed, community members may have concerns that ice throw can be potentially hazardous and pose risks to them or their property. Naveco takes pride in supporting all phases, including the development, construction, and operation of all projects. This includes Naveco’s assurance that we fully consider all concerns of potential hazards and risks are fully, and we meet safety requirements. If icing occurs, it may affect wind turbine operations and maintenance in different ways. For instance, if ice accretes on rotor blades, it reduces the aerodynamic performance of the turbine and is likely to induce production losses. Also, rotor blade icing increases vibrations and fatigue loads and can reduce turbine lifespan. However, the risk of being struck by an ice piece thrown for the blade when standing outside of the ice throw zone is considered null. Within the ice throw zone, this risk increases as one gets closer to the turbine.
De-Icing Systems on Wind Turbines
The risk for potential harm from ice throw is decreasing as a new state of the arch de-icing technology is being developed every year. Wind turbines manufactures are constantly developing technology to adapt to different climate conditions, including Canada, where icing is more common. Enercon, a global leader in wind turbine manufacturing, has developed impressive de-icing turbine blade technology in recent years.
There are options in place for wind turbines to have internal heaters to shorten thawing time. A fan heater installed in the blade root is activated and starts heating the air inside the rotor blade using air recirculation. The temperature of the blade surface warms up to above 0°C and the ice build-up melts off.
Ice throw can be potentially harmful to the safety of individuals and the energy production of a wind farm. The risk of being struck by a piece of debris from ice throw is zero when all safety requirements are met. New turbine technologies are now available that maximize energy yield, reduce downtime, and reduce risk.
ENERCON Ice Detection System
Enercon wind energy converters are equipped as standard with an ice detection system. During operation the ice detection system compares current operating data such as wind power and blade angle with the recorded long-term mean values. The system can detect any build-up on the machine as it changes the aerodynamic properties. The system is brought to a halt and de-icing procedures are initiated.
The risk for potential harm from ice throw is decreasing as a new state of the arch de-icing technology is being developed every year.
About the Author
Mariah was born and raised in New Brunswick, moving to Fredericton from Darlings Island. She attended St. Francis Xavier University to obtain a Bachelor’s Degree in interdisciplinary studies in Aquatic Resources with Public Policy and Social Research.
She then went on to further her education by enrolling in the University of New Brunswick, where she graduated with a Master of Environmental Management.
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