The Illinois Pollution Control Board says Ameren Corp. can't transfer a variance allowing it to delay pollution controls at coal-fired plants to a company that has agreed to buy them.
The board voted 4-0 on Thursday to deny a request from Ameren and Dynegy Inc.
Houston-based Dynegy announced in March that it would acquire Ameren's five Illinois coal plants. But it also wanted to assume a pollution-control variance that Ameren was granted last year.
Ameren won a five-year delay in a requirement that it install soot-control equipment at the plants after claiming a financial hardship.
But the Pollution Control Board says Dynegy must make the case on its own merit if it wants a variance.
Calls to Ameren and Dynegy on Thursday seeking comment were not immediately returned.