A field study conducted by researchers from Iowa State University and North China Electric Power University examined the formation and operational impacts of ice accumulation on wind turbines. Even light icing can produce enough surface roughness on wind turbine blades to reduce their aerodynamic efficiency, which reduces the amount of power produced, as Texas experienced in February 2021.

Frequent severe icing can cut a wind farm's annual energy production by over 20%, costing the industry hundreds of millions of dollars. The uneven accretion of ice on blades also creates imbalances, causing turbine parts to wear out more quickly and inducing vibrations that cause the turbines to shut down.Ice accumulation can be nearly a foot thick on blade tips. Source: Hui Hu/Iowa State UniversityIce accumulation can be nearly a foot thick on blade tips. Source: Hui Hu/Iowa State University

Ice formation was monitored at a 34-turbine, 50 MW wind farm on a mountain ridgetop in eastern China. Drones equipped with high-resolution digital cameras were deployed to take pictures of the 50 m long turbine blades after exposure to 30 hours of icy winter conditions. The photographs allow detailed measurement and analyses of how and where ice collects on the turbine blades and can be evaluated with turbine production data to reveal how ice impacts power output.

Ice was observed to form over the entire span of the blade, with the largest amount found near the tips. Accretions of as much as a foot thick were documented and the turbines produced only 20% of normal power during the event.

The researchers are advancing a preventive technology that electrically heats the leading edges of wind turbine blades layered with water- and ice-repelling coatings.

A paper on the study appears in Renewable Energy.

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