Leading Edge Erosion: When Precipitation Destroys Wind Turbine Blades

Erosion is all around us, from the meandering course of rivers and other waterways, to the gradual carving out of channels in even the toughest mountains, and the softening of features in statues. Yet generally we expect erosion from precipitation to be gradual and gentle, taking decades to make a noticeable difference. This of course takes into account gentle flows and the soft pitter-patter of rain on stone, not turbine blades passing through the air at many times the terminal velocity of rain drops of up to 9 m/s.

As wind turbines have increased in size and diameter of their blades, this has noticeably increased the speed of especially the blade tips. With more and more wind turbine blade tips now exceeding speeds of 100 m/s, this has also meant a significant increase in the impact of rain drops, hail and other particulates on the lifespan of these turbine blades. As comparison, 100 m/s is 360 km/h (224 mph), which is only slightly slower than the top speed of a Formula 1 car.

The effect of turbine blade leading edge erosion (LEE) not only decreases aerodynamic efficiency, but also invites premature failure. Over the past years, special coatings and leading edge tapes have been developed that act as sacrificial surfaces, but as wind turbines only keep getting larger, so does the effect of LEE. Beyond simply replacing LE tape every year on every turbine, what other options are there?

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Can We Repurpose Old Wind Turbine Blades?

Wind turbines are a fantastic, cheap, renewable source of energy. However, nothing lasts forever, and over time, the blades of wind turbines fatigue and must be replaced. This then raises the question of what to do with these giant waste blades. Thankfully, a variety of projects are exploring just those possibilities.

A Difficult Recycling Problem

Around 85% of a modern wind turbine is recyclable. The problem is that wind turbine blades currently aren’t. The blades last around 20 to 25 years, and are typically made of fiberglass or carbon fiber. Consisting of high-strength fibers set in a resin matrix, these composite materials are incredibly difficult to recycle, as we’ve discussed previously. Unlike metals or plastics, they can’t just be melted down to be recast as fresh material. Couple this with the fact that wind turbine blades are huge, often spanning up to 300 feet long, and the problem gets harder. They’re difficult and expensive to transport and tough to chop up as well.

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