It's a relatively very minor challenge compared to burning massive amounts of gas, coal or oil for the same energy of the blades over the lifetime. The big picture is that wind turbines are a massive improvement over that.

There's a very minor challenge (compared to decades of coal/gas related emissions) of what happens to the blades after their useful life ends. Mostly you are just putting something that doesn't naturally degrade very well in a landfill where it sits and doesn't degrade very well. It might be leaking some toxic stuff slowly over a very long time. Compared to all absolutely massive amounts of other stuff we dump in landfills, what happens to the blades is probably not the most urgent thing to tackle from an ecological point of view.

Of course, windmill construction at scale involves a lot of steel, concrete, and blades. So if would can do the same job and perform well, that's still interesting to do. We take something that's already amazingly good and make it even better.