[Animats]

Since they are the tallest thing around, wind turbine blades get struck by lightning regularly. Fiberglas is an insulator. Aluminum is a good conductor. But carbon fiber is a resistor. Carbon fiber blades have to have embedded conductors to prevent from being blown up by lightning strikes. So there's a layer of aluminum foil or similar to provide a low-resistance discharge path.

Same problem as carbon-fiber aircraft, with similar solutions.