I know what I would do to re-purpose them but I'm a genius so the solution took seconds.
I'd fill them with rebar, a PVC conduit and concrete and use them as utility or street light poles.
The general design of wind turbine blades seems to be fibreglass with a so called "hollow centre"
and that apparently gets filled up with styrofoam or urethane to keep water from condensing and building up in them
See the photo I attached to this post.
Thus it seems unlikely that it would be easy or economical to fill in an old blade with cement!
In addition - there might be issues with using them as street poles in cold countries as the buried base sections
would possibly fill with water and be subject to freeze/thaw cycles that would rupture and weaken the blades?
Just some thoughts............ re a not to shabby idea..............