Comment period on EPA’s ACE rule to close Oct. 31

By Erin Voegele | October 25, 2018

The public comment period on U.S. EPA’s Affordable Clean Energy Program (ACE rule) closes in less than a week. More than 1.4 million comments have already been filed. Those who wish to weigh in on the rulemaking have until Oct. 31 to file comments.

The EPA released a prepublication version of the ACE rule on Aug. 21. The rule aims to replace the Clean Power Plan, which the EPA proposed to repeal last year. It establishes emissions guidelines for states to develop plans to address greenhouse gas emissions (GHG) emissions from existing coal-fired plants.

Information released by EPA indicates one major difference between the CPP and the ACE rule is that the CPP promoted disinvestment in coal in favor of renewables and natural gas, and relied on fuel switching. Alternatively, the ACE rule promotes investments to make coal plans cleaner and more efficient and does not promote fuel switching.

According to the EPA, the ACE rule defines the best system of emission reduction (BSER) for existing power plants as on-site, heat-rate efficiency improvements. It also provides states with a list of candidate technologies that can be used to establish standards of performance and be incorporated into their state plans. In addition, ACE updates the new source review (NSR) permitting program to further encourage efficiency improvements at existing power plants and gives states time and flexibility to develop their state plans.

The ACE rule also briefly addresses biomass. While the proposal does not include cofiring as BSER, the agency does propose that biomass cofiring be allowed as a compliance option that states may consider. The rule also references an April 23 April 23 policy announcement by the EPA in which the agency said biomass from managed forests will be treated as carbon neutral when used for energy production at stationary sources.

The EPA opened a 60-day comment period on the ACE rule on Aug. 31. In early September, the agency announced plans to hold a public hearing on the rulemaking on Oct. 1 in Chicago. At that time, the EPA also said it would extend the public comment period for one day, from Oct. 30 to Oct. 31 to allow for 30 days of public comment following the public hearing.

As of Oct. 25, information posted to shows that more than 1.41 million comments have already been filed on the rulemaking. Comments can be filed online at under EPA-HQ-OAR-2017-0355 through Oct. 31.