Four companies that own coal-powered or natural gas electricity generating plants in Illinois filed a lawsuit Tuesday in U.S. District Court, Chicago, to stop Illinois’ Future Energy Jobs Act that Gov. Bruce Rauner signed into law in December.

The suit alleges that Exelon’s nuclear generating plants in Cordova and Clinton, Illinois, could not compete in the energy markets and forced the state to bail out the company by overcharging electricity consumers millions of dollars.

According to the suit, the Future Energy Jobs Act “intrudes on the exclusive authority of the Federal Energy Regulatory Commission over the sale of electric energy at wholesale in interstate commerce pursuant to the Federal Power Act.”

The current auction-based markets for wholesale electric energy sales in Illinois that is approved by the Federal Energy Regulatory Commission benefited consumers but “impaired the financial liability” of the Exelon facilities, according to the suit.

Exelon, the suit states, threatened to close the plants unless the state bailed out the company with “billions of dollars in subsidies, to be paid by Illinois electricity consumers.”

Seeking to change the results of the market-based auction system, the suit states, the Illinois General Assembly enacted the Future Energy Jobs Act to prop up “these two uneconomic nuclear power plants and keep them in the market for at least 10 more years” via so-called Zero Emission Credits.

Unless stopped, the suit states, the credits will result in Illinois’ “captive ratepayers overpaying an estimated $235 million per year over 10 years to Exelon.”

Closing the Cordova plant would have meant the loss of 800 jobs, Exelon said. It also would have meant fewer tax dollars for school districts near the plants, as well as for Rock Island County. Exelon is Rock Island County’s largest taxpayer.

The lawsuit was brought by two Houston-based companies, Dynegy Inc. and Calpine Corp., as well as Eastern Generation LLC of Stamford, Connecticut, NRG Energy Inc. of Princeton, New Jersey, and the Electric Power Supply Association headquartered in Washington, D. C.

The suit names as defendants Anthony Star, director of the Illinois Power Agency, as well as the five commissioners of the Illinois Commerce Commission.

A spokesman for Exelon could not be reached for comment Tuesday night.