Jacksonville-based cooperative Prairie Power says the farm could generate electricity for about 16,000 rural customers.
Construction at a site along the Illinois River about 70 miles west of Springfield would start next year. And electricity production would begin in 2011.
The co-op already operates a coal-fired power plant and natural-gas plant. But this is its first foray into wind energy.
Prairie Power executive Robert Reynolds says the co-op plans to sell clean-energy bonds to finance the project. The bonds include a federal tax credit.
Pike County currently has just one wind turbine, built in 2004.