The major coal-fueled electric generating station and coal mine is being planned for Washington County by Peabody Energy.
"The permit marks a major milestone in the development of the project," Peabody executive vice president of corporate development Roger Walcott Jr said.
"It is a testament to Peabody's commitment to create clean, environmentally friendly energy in Illinois."
Prairie State received its air permit following three years of rigorous environmental review, multiple public comment periods and extensive community input.
The project will invest more than $500 million in control technologies, enabling the plant to use abundant Illinois coal reserves while achieving very low emissions levels.
