EPA aims to roll back greenhouse gas and mercury emission rules

US Environmental Protection Agency administrator Lee Zeldin on Wednesday announced two EPA proposals to roll back emission limits for power plants on greenhouse gases, mercury, and particulate matter. Under one proposed rule, the EPA would repeal all greenhouse gas (GHG) emission standards for fossil fuel–fired power plants, undoing standards instituted during the administrations of Barack Obama and Joe Biden for new and existing plants. A second proposal would undo Biden-era rules to tighten the Mercury and Air Toxics Standards (MATS) for power plants and return them to 2012 standards. The proposals come almost 3 months after Zeldin said the EPA is reviewing 31 regulatory actions for potential rollback.

“Today is a historic day for the EPA,” Zeldin said during the announcement. “We are proposing to repeal Obama and Biden rules that have been criticized as regulating coal, oil, and gas out of existence.” The proposed changes will ensure that people in the US will have access to plentiful and cheap electricity, he said. “Today, EPA is taking an important step reclaiming sanity and sound policy illustrating that we can both protect the environment and grow the economy.”

The proposed changes could impact the chemical industry and other sectors of the economy by reducing the price of power. “Ensuring affordable and reliable energy supplies drives down the costs of transportation, heating, utilities, farming, and manufacturing while boosting our national security,” the EPA says in a press release.

Under the Clean Air Act, the EPA is required to regulate industrial sources if they’re a significant contributor to air pollution, says Jeffrey Holmstead, former assistant administrator of the EPA’s Office of Air and Radiation and now a lawyer at the firm Bracewell. In the GHG proposal, the agency argues that emissions from US fossil fuel–fired power plants don’t qualify as a “significant” source of global GHG emissions, although the proposal doesn’t give the current amount of emissions. The EPA suggests that the definition of a significant emissions should be determined by “the impacts and effects of statutory policy considerations” rather than by a quantitative measure of volume of GHG emissions. A recent study by the Institute for Policy Integrity found that the US power sector contributed 5% of global GHG emissions between 1990 and 2002. If it were a country, the sector would have been the sixth-biggest global emitter of GHGs in this time frame. 

“It’s not terribly surprising that that’s the route they’re taking for power plants,” Holmstead says. What counts as ‘significant’ isn’t a scientific issue but more of a judgment call, he says. And it’s one that the current EPA is going to make, according to Zeldin. After the proposed rule goes through a public comment period, “we will make a decision on whether or not it is a significant contributor,” Zeldin said during a question-and-answer period with reporters after the announcement. “It is a decision I will have to make at the end of this process, and I look forward to doing so,” he said.

The EPA’s proposal indicates that the changes to GHG emission standards would save the power sector about $1.2 billion a year over the next 20 years.

Zeldin also announced Wednesday that the EPA is proposing to eliminate another restrictions on how much mercury and other toxic compounds power plants can release into the air. In 2024, the Biden administration passed tighter limits under the MATS rule, reducing the amount of filterable particulate matter and Hg that coal-fired electric plants could emit by about one-third each. When promulgating that rule, the EPA said that tighter restrictions on these emissions were especially important to protect children’s developing brains and in communities near power plants who regularly eat fish with high accumulated levels of the pollutants.  The agency projected then that this tighter MATS rule would create $300 million in total health benefits and $130 million in climate benefits between 2028 and 2037.

In the proposal for the new rule, the EPA says that the revisions to the MATS rule weren’t necessary, “as they impose large compliance costs or raise potential technical feasibility concerns.” The agency says that repealing the 2024 MATS amendments would save about $120 million a year in regulatory costs over the next 10 years, or a total of about $1.2 billion.

“The Trump EPA’s proposed repeal of these life-saving clean air protections is dangerous to the health, safety and well-being of all Americans,” Vickie Patton, general counsel of the advocacy group the Environmental Defense Fund, says in a statement. “Power plants are already among the largest sources of mercury, toxic and climate-destabilizing pollution in the nation, and these proposals would allow them to pour more of that pollution into our air. These pollutants are associated with deaths, serious illnesses and hospitalizations, and increased medical costs. The Trump EPA is pursuing this irresponsible action even though we have widely available technologies that allow power plants to reduce pollution with proven cost-effective solutions.”

The US Chamber of Commerce supports the proposed changes. “While we are reviewing the full proposal, the voiding of the prior rule would remove a barrier to producing the electricity generation needed to maintain our domestic energy security and our competitive edge in critical fields like artificial intelligence,” Marty Durbin, president of the US Chamber’s Global Energy Institute, says in a statement.

The EPA will hold a public hearing about both proposed rules 15 days after they appear in the Federal Register, and the proposals will be open for public comment for 30 days after the publication date.