In 2001, the Department of Energy's Wind Program and the National Renewable Energy Laboratory (NREL) published these wind windpower maps for the map of Illinois. The maps show wind speed estimates at 50 meters above the ground and depict the windpower that could be used for large scale wind development.

The wind resource information is presented in two formats. Both formats show the wind supply using NREL's standard wind power classification system, in relation to transmission lines and major cities. Version 1 shows the wind windpower at all levels all the way through the map, and Version 2 highlights the best areas suitable for large scale wind energy development which are primarily positioned in central and northern Illinois. At least five prime wind zones are identified (southeast of Quincy, Bloomington area, north of Peoria, Mattoon area, and between Sterling and Aurora), as well as other potential sites.

The wind potential from these best areas is about 9000 MW of installed wind generation capacity. These areas represent about 1.2% of Illinois' land and are largely rural agricultural areas. Each square kilometer of windy land may support about 5 MW of installed wind capacity. All urban and environmentally-sensitive lands (state parks, wildlife refuges, etc) have been excluded in estimating the wind potential.

Given recent advances in technology and wind turbine hub-heights of 80 m and higher that are now being installed, many additional zones in Class 3 areas may be suitable for large scale wind development especially in places where strong wind shear may exist. Therefore, we expect that wind potential estimates for heights of 80 to 100 m may be considerably greater than the estimates given here for the 50-m height.