According to a press release repeated on boatnerd.com, those blades
are headed to a Horizon Wind Energy windmill farm in Payne, Ohio. The
blades are from Vestas, a Danish wind turbine manufacturing company.
There are two more ships headed to Burns Harbor with more blades. One
is the Aragonburg which is currently in Lake Ontario approaching the
Welland Canal. Unfortunately, I probably won't be able to see this
ship.

Once unloaded, the Avonborg is expected to load corn & barley in
Hamilton Ontario to be taken to Puerto Rico.

It's fascinating what some of these ships carry, and where they go.

Steve