22 US states and 7 local governments sue EPA over ACE rule

A coalition of 22 states and 7 local governments of the United States has filed a lawsuit against the US Environmental Protection Agency (EPA) over its “Affordable Clean Energy” (ACE) rule, which replaced the Clean Power Plan in June 2019, considering that the new rules would prolonge the country's dependence on coal-fired power plants and obstruct the transition toward renewable power generation. In addition, it would fail to reduce CO₂ emissions from the US power sector to the extent needed to limit global temperature increase to less than 2°C.

In late June 2019, the US EPA issued the final version of the ACE rule, which sets emission guidelines for states when developing plans to cut CO₂ emissions at their coal-fired power plants and identifies heat rate improvements as the best system of emission reduction (BSER) for CO₂ at coal-fired power plants. The EPA expects the ACE rule to cut CO₂ emissions by 11 Mt in 2030, without harming coal-fired power plants that are facing the competition of gas and renewables. The Clean Power Plan aimed to slash power plant CO₂ emissions by more than a third from 2005 levels by 2030, which would have forced utilities to drop coal in favour of cleaner fuels like natural gas. The regulation was never enacted because of lawsuits by some states and was stayed by the Supreme Court in 2016.

The 22 states and 7 local governments suing the EPA are the following: California, Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Jersey, New Mexico, New York, North Carolina, Oregon, Pennsylvania, Rhode Island, Vermont, Virginia, Washington, Wisconsin, and the District of Columbia, and the chief legal officers of Boulder, Chicago, Los Angeles, New York City, Philadelphia, and South Miami.