Winter is supposed to be the best season for wind power. Winds are stronger, and since air density increases as the temperature drops, more force is pushing on the blades. But winter also comes with a problem: freezing weather.
Frequent severe icing can cut a wind farm’s annual energy production by超过20％, costing the industry hundreds of millions of dollars. Power loss isn’t the only problem from icing, either. The uneven way ice forms on blades can create imbalances, causing a turbine’s parts to磨损更快。它还可以诱导导致涡轮机关闭的振动。在极端结冰的情况下，重新启动涡轮机几个小时可能是不可能的。
Not all ice is the same
For example,rime icing当微小的过冷水滴形成时形成，通常发生在具有相对干燥空气和较冷的温度的区域中，在20°F下。这就是我们通常在冬季的Iowa和其他中西部州看到的东西。
Tempests in a wind tunnel
Building a wind power operation that can thrive in icy conditions requires a keen understanding of the underlying physics, both of how ice forms and the performance degradation that results from ice building up on turbine blades.
To explore those forces, we use a special wind tunnel that can demonstrate how ice forms on samples of turbine blades, and fly camera-equipped drones.
Using the结冰研究隧道at Iowa State University, my team has been replicating the complex 3D shapes of ice forming on turbine blade models in different environments to study how they affect the wind and the blades. Ice can create massive气流分离。In airplanes, that’s a dangerous situation that can cause them to stall. In wind turbines, it reduces theirrotation speed and the amount of powerthey can produce.
我们也study wind turbines in operation around the country当他们面临他们最艰难的条件时。
虽然冰可以在整个刀片上形成，但在尖端附近找到了更多的冰。经过一个30小时的结冰事件，我们发现冰厚厚。尽管风高，但冰重型涡轮机旋转得多，甚至关闭。涡轮机生产only 20% of their normal power在那个时期。
Keeping ice off blades
There are a few reasons the strategies that effectively keep ice off aircraft wings aren’t as effective for wind turbine blades.
Most current wind turbine anti-icing and de-icing methods remove ice buildup through电热or blowing hot air inside. Heating these massive areas, which are many times larger than airplane wings, adds to the cost of the turbine and is inefficient and energy-consuming. Composite-based turbine blades can also be easily damaged by overheating. And there’s another problem: Water from melting ice may simply run back and refreeze elsewhere.
寒冷天气地区的另一种策略是使用surface coatingsthat repel water or prevent ice from sticking. However, none of the coatings has been able to eliminate ice completely, especially in critical regions near the blades’ leading edges.
A better solution
我的团队已经开发出一种新颖的方法es elements of both technologies. By heating just the critical regions—particularly the blades’ leading edges—and using water- and ice-repelling coatings, we were able to reduce the amount of heat needed and the risk of running back water to refreeze over the blade surfaces. The result effectively prevents ice from forming on整个表面涡轮叶片。
In comparison to the conventional brute-force surface-heating methods, our hybrid strategy also used much less power, resulting in up to 80% energy savings. Without ice to slow it down, the turbines can produce more power through the winter.