The move is a setback for the developer, local officials, property owners around Elizabeth City, near the Atlantic coast, and Governor Bev Perdue, who viewed the project as one of the most promising for bringing wind power to the southeast state.
Perdue, a Democrat, is seeking a second four-year term in November and has emerged as a leading supporter of renewable energy in North Carolina.
Iberdrola, the second-largest wind developer in the US after NextEra Energy Resources, has spent millions of dollars since 2009 studying environmental impacts and wind resource at the site.