Wisconsin Attorney General Josh Kaul has joined a coalition of 22 states and seven local governments in a lawsuit challenging the federal Environmental Protection Agency’s (EPA) Affordable Clean Energy (ACE) Rule, which repeals the Clean Power Plan. EPA proposed repealing the Clean Power Plan in 2017 after determining the rule exceeds EPA’s statutory authority and is inconsistent with the Clean Air Act. As a replacement, EPA finalized the ACE Rule in June.

The newly finalized ACE rule provides states guidelines to develop plans to reduce greenhouse gas emissions from power plants. Whereas the Clean Power Plan forced states to comply with a single federal standard, the ACE rule gives states flexibility to set their own standards within the boundaries of the federal guideline. The proposed rule gives states three years to develop plans and provides a list of six “candidate technologies” for states to incorporate in their plans.

The ACE rule also defines the “best system of emission reduction” for existing power plants as on-site heat efficiency improvements. The best system of emission reduction is used in setting the standard of performance under the Clean Air Act.

With the implementation of the ACE rule, EPA expects CO2 emissions to decrease by as much as 35 percent below 2005 levels. The agency estimates the ACE rule will result in annual benefits of $120 million to $730 million including costs, climate benefits, and health benefits. A previous regulatory impact analysis from EPA estimated that the ACE rule would reduce compliance costs alone by up to $400 million annually compared to the Clean Power Plan.

The attorneys general filed a petition for review on Aug. 13 asking the U.S. Court of Appeals for the D.C. Circuit to declare the ACE rule unlawful and vacate it. (AG Kaul press release)