Dynegy (NYSE: DYN) was bankrupt a year ago yet faces huge environmental regulations in the state of Illinois on the heels of the company's attempt to acquire coal assets from Ameren (AEE 0.74%) in that state. Shares of Dynegy have largely been out of favor with investors who have preferred bidding up more well-known natural gas names such as EOG Resources (EOG -3.29%), Devon Energy (DVN -3.92%), and Apache (APA -2.23%). However, any approval by the Illinois Pollution Control Board to give Dynegy five years to meet environmental standards for coal-fired power plants in Illinois could create a bullish momentum play for those investing in energy, especially if natural gas prices move upward this winter, considering the company's trading pattern is correlated with the direction of natural gas futures.