EPA Finalizes Pollutant-Specific Significant Contribution Finding For Greenhouse Gas Emissions From New, Modified, And Reconstructed Electric Utility Generating Units

Today, the United States Environmental Protection Agency (EPA) is providing a clear framework for determining when standards are appropriate for emissions of greenhouse gases from specific source categories under Clean Air Act (CAA) section 111(b)(1)(A). The framework provides criteria – primarily an emissions threshold – for evaluating whether greenhouse gas (GHG) emissions from a source category are significant and should be regulated. The rule clarifies a previously vague standard, promotes regulatory certainty for stakeholders, and ensures consistency in evaluating when to regulate under this part of the CAA.

“EPA’s new significance framework lays out how the agency will determine when stationary sources of greenhouse gases trigger a requirement by the agency to set New Source Performance Standards in the future,” said EPA Administrator Andrew Wheeler. “This action adheres to the specific requirement laid out in the Clean Air Act and ensures covered entities, such as power plants and other large-scale manufacturers, are provided a clear view of regulatory requirements and expectations.”

Today’s framework follows up on a finding from the 2020 Oil and Gas Rule, which determined that, in order to regulate emissions of any pollutant from a stationary source category under the CAA section 111(b)(1)(A), EPA must first find that emissions of that pollutant from that source category contribute significantly to dangerous air pollution. This is called a pollutant-specific “significant contribution finding.” In the 2020 Oil and Gas rule, EPA stated that it intended to identify criteria for making a pollutant-specific significance finding in a separate rulemaking. Today’s action fulfills that commitment.

EPA’s framework sets an emissions threshold of 3 percent of total gross U.S. GHG emissions as the primary criterion in making a pollutant-specific significance determination for purposes of CAA section 111(b). The framework provides that source categories can only be considered to contribute significantly to dangerous air pollution due to their GHG emissions if the amount of those emissions exceeds 3 percent of total U.S. GHG emissions. For certain source categories that emit above this threshold, EPA’s framework also provides secondary criteria that can be used to further evaluate whether a source category contributes significantly.

In this action, EPA is also determining that the electric utility generating units (EGU) source category (which includes utility boilers, gasification units, and stationary combustion turbines) contributes significantly to dangerous air pollution because GHG emissions from the EGU source category are substantially above the 3-percent threshold. EGUs stand out as by far the largest stationary source of the U.S. GHG emissions, emitting over 25 percent of all the U.S. GHG emissions.

More information is available on the web at https://www.epa.gov/stationary-sources-air-pollution/nsps-ghg-emissions-new-modified-and-reconstructed-electric-utility.

Background
In December 2018, EPA proposed revisions to the GHG NSPS from new, modified, and reconstructed fossil fuel-fired power plants. EPA held one public hearing and received more than 142,000 comments on the proposal.

In the December 2018 proposal, EPA solicited comment on whether to make a pollutant-specific significant contribution determination for GHG emissions from EGUs, which is the subject of this final action. The remainder of the proposal was dedicated to the issue of the determination of the best system of emission reduction, or BSER, for newly constructed, modified, and reconstructed coal-fired EGUs. EPA is not addressing that aspect of the proposal, or related comments, in this final rulemaking.