Exelon Generation plans to invest more than $300 million in capital projects to upgrade its nuclear power plants in Illinois as a result of sweeping clean energy legislation passed last month.

Gov. J.B. Pritzker in mid-September signed Senate Bill (SB) 2408 to put Illinois on a path toward 100% renewable energy by 2050. The bill provides nearly $694 million in subsidies over five years for the Exelon Corp. subsidiary’s Byron, Dresden and Braidwood nuclear stations, which had previously been slated for retirement.

The bill has major implications for natural gas as well, requiring all private gas-fired units to reach zero emissions by 2045. Municipal gas-fired units must reach zero emissions by 2045 as well, unless companies convert them to run on green hydrogen or similar...