On June 11, 2025, EPA Administrator Lee Zeldin announced two proposals to repeal all greenhouse gas (GHG) emissions standards for the power sector under Section 111 of the Clean Air Act (CAA) and to repeal amendments to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Coal- and Oil-Fired Electric Utility Steam Generating Units, commonly known as the 2024 Mercury and Air Toxics Standards (MATS).
GHG emissions standards for the power sector
The EPA is proposing to repeal all GHG emissions standards for fossil fuel-fired power plants. It’s reasoning states that the CAA “requires it to make a finding that GHG emissions from fossil fuel-fired power plants contribute significantly to dangerous air pollution, as a predicate to regulating GHG emissions from those plants,” according to the proposed regulation. It further proposes “to make a finding that GHG emissions from fossil fuel-fired power plants do not contribute significantly to dangerous air pollution.”
Many industry analysts are shocked at this finding, as the EPA’s website directly contradicts this information. An EPA webpage entitled Human Health & Environmental Impacts of the Electric Power Sector, dated February 6, 2025, states:
“Fossil fuel-fired power plants are also a significant source of emissions of carbon dioxide (CO2), an important greenhouse gas. … Electric power generation is the second largest emitter of carbon dioxide pollution, contributing to climate change, which is threatening public health and affecting ecosystems at multiple levels, from the biological communities that make up ecosystems to the services they provide to communities, economies, and people.”
And, an article by Health and Me says, “The report also highlights mercury emissions from power plants as a significant threat to children’s neurological development.”
Alternatively, the EPA proposes “to repeal a narrower set of requirements that includes the emission guidelines for existing fossil fuel-fired steam generating units, the carbon capture and sequestration/storage (CCS)-based standards for coal-fired steam generating units undertaking a large modification, and the CCS-based standards for new base load stationary combustion turbines.”
As part of this alternative proposal, the Agency is taking comments on the efficiency-based requirements for new natural gas power plant requirements. Comments can be submitted on the Federal e-Rulemaking Platform until August 7, 2025, under Docket ID No. EPA–HQ–OAR–2025–0124.
If finalized as proposed, these actions will repeal the 2015 emissions standards for new fossil fuel-fired power plants issued during the Obama-Biden administration and the 2024 rule for new and existing fossil fuel-fired power plants issued during the Biden-Harris administration.
“Unlike other air pollutants with a regional or local impact, the targeted emissions are global in nature,” an Agency news release says. “As a result, any potential public health harms have not been accurately attributed to emissions from the U.S. power sector.”
The EPA estimates this proposal will save the power sector $19 billion in regulatory costs over two decades beginning in 2026, or about $1.2 billion a year.
Section 111 background
Authority to set power plant GHG emissions limits was initially provided by the Obama administration’s Clean Power Plan (CPP) to establish “flexible and achievable standards to reduce carbon dioxide emissions” that included “carbon pollution reduction goals for power plants and [enabled] states to develop tailored implementation plans to meet those goals …”
“Soon after, 18 of the 50 U.S. [states] joined a legal challenge against the emissions limits,” notes energy industry news site Power Technology. “Led by West Virginia politicians, the legal case said that the Plan gave the EPA massive power to reshape the U.S. economy. Opposers often say that state governments should decide emissions limits, not federal agencies.”
The question in West Virginia v. EPA was whether Congress constitutionally authorized the EPA under Section 111(d) of the CAA to “issue significant rules including those capable of reshaping the nation’s electric grids and unilaterally decarbonizing virtually any sector of the economy – without any limits on what the agency can require so long as it considers cost, non-air impacts and energy requirements?”
The 6–3 decision ruled that it’s Congress rather than the EPA that has the authority to create cap-and-trade regulations systems to limit GHG emissions from existing sources and transition away from fossil fuel energy to clean energy. The U.S. Supreme Court (SCOTUS) enacted a stay on the CPP in 2016.
“Former President Trump’s Administration put the CPP under review, removed its funding and passed legislation to undermine it,” the Power Technology article continues. “Then, his administration issued the Affordable Clean Energy (ACE) rule, which prioritized low-cost power generation, and called for less emissions regulation.”
However, in January 2021, a divided D.C. Circuit Court of Appeals sent the Trump administration rule back to the EPA’s drawing board, stating the rule was devised through a “tortured series of misreadings” of the CAA. This left it up to the Biden administration to create a new rule.
“The Biden Administration issued its own rule in 2024, which many critics say is just another attempt to achieve the unlawful fuel-shifting goals of the [CPP],” the EPA’s release adds.
The Biden regulations “finalized the first-ever standards to limit carbon pollution from new gas and existing coal-burning power plants,” according to an Earthjustice press release.
These regulations required all coal-fired plants planning to run long term and all new baseload gas-fired plants to control or capture 90 percent of their carbon pollution.
“Fossil-fueled power plants are the largest industrial source of climate pollution, responsible for more than 30% of U.S. carbon pollution, as well as other dangerous air pollution that harms our health,” according to Earthjustice.
“Carrying out the requirements to reduce [GHG] emissions by that much would require a level of carbon capture and storage (CCS) that has never been successfully achieved. … Utility industry representatives, such as the Edison Electric Institute, have warned that the technology ‘is not yet ready for full-scale, economy-wide deployment.’ The institute added that there is not enough time to put everything in place by Biden’s 2032 deadline,” explains the Mackinac Center for Public Policy.
Proposal to repeal certain amendments to the MATS
The EPA is also proposing to repeal certain amendments to the MATS for power plants issued on May 7, 2024. The proposal calls for reverting to “2012 MATS standards that have driven sharp reductions in harmful air toxic pollutants from coal- and oil-fired power plants,” the EPA news release says.
This action proposes to relieve all facilities of:
- The more stringent filterable particulate matter (PM) emissions standard for coal-fired electric generating units (EGUs)
- The tighter mercury standard for lignite-fired EGUs
- The requirement to use PM Continuous Emissions Monitoring Systems (CEMS)
“EPA proposes to repeal the rulemaking because the 2024 rulemaking incorrectly determined that the revisions met the statutory test for ‘necessary’ under Section 112(d)(6),” notes law firm Vinson & Elkins LLP. “EPA asserts that because previous risk assessments show that the 2012 standards ‘provided an ample margin of safety’ to protect public health, further tightening of standards would not result in meaningful additional health benefits.”
MATS background
The CAA requires the EPA to complete a “risk and technology review” every eight years for each standard adopted under Section 112 of the Act.
According to the Agency’s release, “The original MATS Rule was promulgated in 2012 and has since been highly effective in protecting public health and the environment. Specifically, 2021 mercury emissions from coal-fired power plants were 90 percent lower than pre-MATS levels. Since 2010, acid gas hazardous air pollutant emissions have been reduced by over 96 percent, and emissions of the non-mercury metals – including nickel, arsenic, and lead – have been reduced by more than 81 percent.”
The Biden administration final MATS rule reduced the mercury emissions limit by 70% for lignite-fired units and reduced the emissions limit that controls toxic metals by 67% for all coal plants. It also required the use of continuous emissions monitoring systems to provide real-time, accurate data to regulators, facility operators, and the public to ensure plants were meeting the lower limits.
When the 2024 MATS amendments were proposed, most of those plants were already achieving lower emissions than the standard.
“The 2024 amendments to the [MATS] proved pointless … the Biden administration’s changes in 2024 did little more than add unnecessary costs,” the Mackinac Center’s blog post states.
According to the current administration, the “2024 MATS rule has caused significant regulatory uncertainty, especially for coal plants in Florida, Illinois, Kentucky, Mississippi, Missouri, Montana, North Carolina, North Dakota, Pennsylvania, Texas, West Virginia, and Wyoming.”
The EPA estimates that this proposed repeal of the 2024 MATS amendments would save $1.2 billion in regulatory costs over a decade, or about $120 million a year.
“These costs are large and unnecessary given the success the industry has already achieved in reducing emissions of mercury and other hazardous air pollutants,” the Agency’s release says.
Presidential exemptions
On April 8, 2025, President Donald Trump signed a proclamation granting many power plants the ability to “operate under whatever existing mercury and air toxics standards they currently are subject to until 8 July 2029,” which is two years after the compliance deadline put in place in May 2024, according to Argus Media. “Most of the plants on the list are coal-fired generators, some of which were scheduled for retirement by the end of 2027.”
Environmentalist litigation
One day after the announced proposal to repeal the two power plant regulations, a group of “12 environmental and community groups filed a lawsuit against the Trump administration over its illegal use of presidential exemptions that allowed 68 coal-fired power plants to postpone complying with tighter standards for mercury, arsenic, and other toxic emissions regulated under the 2024 MATS,” an Environmental Defense Fund (EDF) press release says.
In March, the press release continues, Zeldin “invited corporations to email the agency to request exemptions from clean air standards.”
“Corporations were told they could cite ‘national security’ or ‘lack of available technology’ as justifications. A month later, two-year exemptions were sent to coal-fired power plants, although many already comply, and pollution controls are installed at most of the plants and are otherwise widely available.”
The coalition’s lawsuit alleges that Trump’s April 2025 proclamation granting pollution exemptions that were requested by e-mail sidesteps any form of public process and contravenes the statutory framework.
“Trump’s power grab hinges on twisting Section 112(i)(4) of the [CAA], a provision never used in 55 years and meant for true national security emergencies where pollution controls are unavailable,” the EDF’s release adds. “His proclamation vaguely cited ‘national security’ and ‘lack of available technology,’ even though many coal plants already meet the MATS and proven pollution controls are widely available.”
The lawsuit was filed in the U.S. District Court for the District of Columbia.
The coal power plants that were granted exemptions are located in 23 states:
- Alabama
- Alaska
- Arizona
- Arkansas
- Georgia
- Illinois
- Indiana
- Kansas
- Kentucky
- Louisiana
- Mississippi
- Missouri
- Montana
- New Hampshire
- North Dakota
- Ohio
- Oklahoma
- Pennsylvania
- South Dakota
- Tennessee
- Texas
- West Virginia
- Wyoming
“Many of the exempted facilities are located in or near working-class communities and communities of color already burdened by pollution.”
“Trump’s EPA is abandoning its responsibility to protect the public and the environment against the many harms of fossil burning power plants,” said Jill Tauber, Earthjustice’s vice president of climate and energy, in the organization’s press release. “Mercury damages kids’ developing brains. Arsenic causes cancer and birth defects. Carbon pollution drives climate change and racks up massive costs. The critical protections that EPA now seeks to undo exist because science and the law demand that EPA act. EPA is giving the fossil fuel industry a pass on its pollution at the expense of our health and our communities.”
The plaintiffs to the lawsuit are Air Alliance Houston, the Clean Air Council, Downwinders at Risk, the Montana Environmental Information Center, and the Sierra Club, represented by Earthjustice; the Center for Biological Diversity; EDF, represented by law firm Donahue, Goldberg & Herzog; Citizens for Pennsylvania’s Future, represented by the Clean Air Task Force; the Environmental Integrity Project; the Dakota Resource Council and Environmental Law and Policy Center (ELPC), represented by the ELPC; and the Natural Resources Defense Council.