New EPA regulations target air, water, land and climate pollution from power plants, especially those that burn coal

PacifiCorp's Hunter coal-fired power plant in Utah is scheduled to shut down by 2032. George Frey/Getty Images

Electric power generation in the U.S. is shifting rapidly away from fossil fuels toward cleaner and lower-carbon sources. State clean energy targets and dramatic declines in the cost of renewable electricity are the most important reasons.

But fossil fuel plants still generate 60% of the U.S. electricity supply, producing air, water and land pollutants and greenhouse gases in the process. To reduce these impacts, the Environmental Protection Agency announced a suite of rules on April 25, 2024. They focus mainly on coal plants, the nation’s most-polluting electricity source.

As an environmental lawyer who has been in practice since the early 1970s, I believe these curbs on power plant pollution are long overdue. The new rules close loopholes in existing laws that have allowed coal-fired power plants to pollute the nation’s air and water for decades. And they require utilities to drastically slash these plants’ greenhouse gas emissions or close them down.

Opponents, including industry groups and Republican attorneys general, have raised concerns, and some have vowed to sue. They argue that the EPA has overreached its legal authority and is imposing crippling costs on the coal industry. While these arguments may resonate with conservative judges, in my view the EPA’s carefully crafted rules are on firm legal ground and have a strong chance of being upheld.

Mercury, wastewater and coal ash

The first rule updates the Clean Air Act’s 2012 Mercury and Air Toxics Standards. Mercury, which is emitted into the air when coal is burned, is a neurotoxin that causes developmental damage in children and has contaminated fisheries throughout the U.S.

The new rule closes the so-called “lignite loophole,” which allows plants burning lignite – the lowest grade of coal – to emit more than three times as much mercury pollution as other coal plants. There are only a handful of lignite plants still operating in the U.S., concentrated in Texas and North Dakota. The new rule lowers the emissions standard for mercury from these plants by 70%.

A second rule tightens standards for wastewater from coal-fired power plants under the Clean Water Act. These plants use a lot of water for cooling, producing steam and industrial processes. The wastewater that they discharge into rivers, lakes and streams contains toxic pollutants such as mercury and arsenic that threaten drinking water supplies and fisheries.

The EPA estimates that the new rule will reduce these pollutants by about 670 million pounds per year. Coal plant owners will have until 2029 to comply, unless they agree to permanently stop burning coal by 2034.

Burning coal also generates millions of tons of ash, which can contain toxic heavy metals such as mercury, arsenic and cadmium. The third new rule deals with “legacy sites” – inactive coal plants – that collectively hold 500 million tons of coal ash in unlined, unmonitored waste pits and holding ponds.

Coal ash spills have contaminated rivers in Tennessee, North Carolina and elsewhere. Over 160 unlined lagoons remain. Most legacy sites are located in low-income communities and communities of color.

The new rule responds to a 2015 ruling by the U.S. Court of Appeals for the D.C. Circuit. The EPA had adopted a rule that regulated coal ash storage at active power plants but not at inactive plants – an approach that the court held was unlawful. The new regulation will require safe management of coal ash at previously unregulated legacy sites.

Carbon pollution standards

The most potentially controversial rule in the new package addresses greenhouse gas emissions from existing coal plants and new gas-fired power plants. Section 111 of the Clean Air Act directs the EPA to define the “best system of emission reduction” for air pollutants, including greenhouse emissions, from power plants. States must then submit plans to the EPA to adopt these systems. If a state refuses, the agency takes over implementation.

The EPA has determined that carbon capture and sequestration is the best system of emission reduction for both existing coal plants and new gas plants. The agency initially proposed to regulate emissions from existing gas plants but is deferring that step.

The rule adopts a staggered approach to compliance that encourages early retirement of the country’s aging coal fleet. Plants retiring before 2032 would not be subject to the rule. Those scheduled to close by 2039 would have to reduce emissions by 16% by 2030. Plants slated to operate beyond 2039 must reduce their greenhouse emissions by 90% by 2032.

To give utilities some flexibility, the rule allows sources to use “green hydrogen” – produced by splitting water using renewable energy – in their fuel mix, and to participate in emissions trading programs.

Next stop: Court

In my opinion, the regulation that faces the most serious legal challenge is the one addressing greenhouse emissions at coal plants. The mercury and coal ash rules simply plug loopholes in existing regulations, and the wastewater rule is a long overdue update of technology standards to control toxic discharges. All three rules are squarely within EPA’s regulatory wheelhouse and grounded in explicit statutory authority.

The climate rule may face a harder road because of the Supreme Court’s 2022 West Virginia v. EPA ruling, which invalidated the Obama administration’s Clean Power Plan and applied a new approach to interpreting laws called the “major question doctrine.” This concept basically says that where a new rule would have “vast economic and political significance,” Congress must explicitly empower the agency with authority over the issue, and the court will not defer to the agency’s interpretation regardless of policy considerations or the agency’s expertise.

The fate of the climate rule may depend on how courts answer these three questions:

– Does the major question doctrine apply?

The EPA has gone to great lengths to distinguish this rule from the ill-fated Clean Power Plan and heed the Supreme Court’s directive to stay in its lane. The new rule takes a traditional, time-tested approach to setting emissions limits based on pollution controls that are available to individual plants.

Indeed, carbon capture and sequestration is analogous to scrubbers – devices that the EPA has required for decades to remove pollutants such as fine particulates, sulfur dioxide and mercury from power plant smokestacks. And the new rule does not require utilities to shift from coal or natural gas to renewable fuels, which was what most troubled the court in the West Virginia case.

– Is carbon capture and sequestration ready for prime time?

The Clean Air Act requires that a best system of emissions reduction must be “adequately demonstrated.” Courts have interpreted this phrase to include options that are forward-looking and “technology-forcing” – meaning that the standards may not be achievable today, but information available now shows they will be achievable in the future.

The D.C. Circuit Court has repeatedly affirmed that the EPA has the “authority to hold the industry to a standard of improved design and operational advances, so long as there is substantial evidence that such improvements are feasible and will produce the improved performance necessary to meet the standard.”

– Will the rule affect power grid reliability?

Shifting too abruptly to new fuels and technologies could make it hard for utilities to generate enough electricity to meet demand. However, the EPA consulted with state and federal agencies and power companies and conducted a detailed analysis, which concluded that the power plant rule would not have a major impact on reliability.

The rule gives owners until 2032 to incorporate carbon capture and sequestration and allows states to keep plants online for an extra year if they can show that retiring them threatens grid reliability. Other provisions give utilities added flexibility.

As of April 2024, there are about 200 coal-burning power plants still operating across the U.S. Plants representing one-fourth of that capacity are projected to close by 2029 for economic reasons unrelated to regulations.

These new rules will certainly make operating coal plants more expensive. This will make the price of electricity generated from coal reflect its true costs to society more accurately. Given coal energy’s impacts on our nation’s air, waters, land and climate, as well as on public health, I see this action as squarely within the EPA’s mission.

The Conversation

Patrick Parenteau does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.