The Michigan wind zone board consultant estimated the potential number of turbines way to low.  The setback distances only limit where turbine foundations are dug.  The useful wind still blows across the "excluded" areas.  The majority of square mile sections in Huron County, which is 800 sq. miles total, could accommodate 6 1.5 MW turbines per section with ease using 60 acre/MW spacing and setbacks the industry supports, and Huron County is only half the 1600 square miles of zone 4.  The technical challenges with huge numbers in the Thumb is transmission and load balancing, not land.