Ask a Scientist: Top Takeaways from the New EPA Carbon Pollution Rules

June 14, 2023 | 3:15 pm
Olivier Lantzendorffer/
Elliott Negin
Senior Writer

Last month, the Environmental Protection Agency (EPA) proposed new power plant carbon pollution standards that, if strengthened, would go a long way to help meet the Biden administration’s goal of slashing carbon emissions in half from 2005 levels by the end of this decade.

Given the EPA has the responsibility and the obligation to address carbon pollution, these standards—the first to limit carbon emissions from existing coal- and gas-fired power plants—are long overdue. Those currently operating fossil fuel plants generate 25 percent of U.S. global warming pollution, second only to the transportation sector. The rule, which also applies to new gas plants, would avoid as much as 617 million metric tons of carbon dioxide through 2042, the EPA calculated, the equivalent of the annual emissions of 137 million passenger vehicles—about half of the cars in the country.

The proposed standards are the most recent in a series of administration policies to address the climate crisis, including new EPA requirements for vehicle tailpipe pollution and methane leaks from oil and gas facilities. Coupled with the Inflation Reduction Act and the bipartisan infrastructure law, the standards would accelerate a transition that is already underway.

No new coal plants have been built in the United States in the last decade and, according to an April report by the Institute for Energy Economics and Finance, this year US coal-fired power plants will likely burn half of what they burned 10 years ago. The report also found that 173 coal plants are scheduled to close by 2030—54 percent of the fleet—and another 55 by 2040.

Meanwhile, between 2012 and 2022, installed wind and solar power more than tripled, according to American Clean Power. Last year, wind generated 10.2 percent of US electricity and utility-scale solar generated 3.4 percent. Add hydropower’s contribution of 6.2 percent, and the 19.8 percent the three renewables generated in 2022 exceeded coal’s output—19.5 percentfor the first time. In 2012, coal generated 37 percent of US electricity.

Coal’s decline and the rapid growth of renewables helped cut the US electricity sector’s carbon emissions by 24 percent over the last decade. But given the urgency of the moment, the coal and gas plants still operating—as well as any new gas plants that come online—will have to dramatically reduce their carbon emissions. The EPA’s new proposed standards would require them to do just that.

To better understand what the EPA’s standards would accomplish, I turned to Julie McNamara, the Union of Concerned Scientists (UCS) Climate & Energy program’s deputy policy director.

EN: First, why are these new standards such a big deal? What would they accomplish?

JM: Quite simply, if we don’t clean up the power sector, we won’t get anywhere close to reducing the amount of carbon emissions needed to avoid the worst consequences of climate change. Not even close. That’s because the power sector is not only an enormous source of carbon pollution today, but also because a cleaned-up power sector is fundamental to decarbonizing a large swath of the rest of our economy by enabling a transition from fossil fuels to clean sources of electricity.

Although the power sector has gotten cleaner in recent years with renewables racing online and coal transitioning off, we’re still, unfortunately, way off the mark. The pieces are in place for a potentially rapid shift to renewables, but to achieve that shift at the pace and scale the science demands, we cannot rely solely on the growth of renewables and the policy leadership of a handful of states. We have to tackle carbon emissions from all coal- and gas-fired power plants head-on.

And that’s exactly what this rulemaking does. It sets a framework for states and utilities across the country to fully reckon with their power plants’ carbon emissions. Coupled with power plant pollution rulemakings addressing other pollutants, including mercury, coal ash, and nitrogen oxides—as well as incentives in new laws for clean energy technologies—the proposed standards have the potential to set a truly climate-aligned transition to a fully clean electricity system that better protects public health and the environment.

EN: These standards—or at least something based on the same Clean Air Act provision—have been in the works for a long time. In 2015, the EPA issued the Clean Power Plan to reduce carbon pollution from power plants, which at the time were the largest source of heat-trapping emissions in the country. Lawsuits by the coal industry and Republican state attorneys general derailed the plan, and the AGs’ suit wound up in the US Supreme Court. What’s the back story?

JM: In fact, the story goes back further than that—much further. The Clean Power Plan was the culmination of years of legal and technical haggling over EPA authority and obligations, including the landmark Massachusetts v. EPA US Supreme Court decision in 2007 and the EPA’s follow-on Endangerment Finding and Cause or Contribute Finding in 2009, which ultimately set the stage for the agency to not only have the authority—but also the obligation—to regulate power plant carbon emissions.

But, as you noted, despite all the groundwork leading up to the 2015 rule, the Clean Power Plan was immediately challenged, and in 2016—before it went into effect—the Supreme Court stayed the rule. The Trump administration subsequently issued its own set of power plant carbon rules in place of the Clean Power Plan, but it was forcefully rejected by the DC Circuit Court of Appeals on the final day of the Trump administration due to its “fundamental misconstruction” of the Clean Air Act. Meanwhile, in 2021, the case against the Clean Power Plan re-emerged, resulting in the West Virginia v. EPA Supreme Court decision in 2022.

There are two key takeaways from West Virginia v. EPA’s 6-3 majority opinion. First, the court did not question the EPA’s authority to regulate power plant carbon emissions. Instead, it restricted the nature and extent of how the agency can exercise that authority, finding that the Clean Power Plan exceeded those boundaries. Second, the majority relied upon the so-called “major questions doctrine” to arrive at its conclusion, the first time the court explicitly referenced the concept. It asserts that for matters of vast economic or political significance, a federal agency must point to explicit congressional authorization.

In other words, if a directive isn’t clearly spelled out in a law, and it’s a “major” issue, then the court will throw out the federal agency rulemaking. The trouble is, Congress has long relied on passing purposefully flexible laws to enable agencies to act on the best available science. This decision would undermine that. Furthermore, the court did not offer any specific metrics or frameworks for when, exactly, it could invoke the doctrine, suggesting that the court manufactured a way to inject itself at-will into the role of policymaker and technical expert, usurping the roles of the other two branches of government.

Looking ahead, while the Supreme Court has upheld the EPA’s authority to regulate heat-trapping emissions from power plants, fossil fuel interests will no doubt continue to mount legal challenges to stall agency progress. And as the West Virginia v. EPA decision made clear, those interests will continue to be welcomed by an increasingly sympathetic court.

EN: What specifically has the EPA proposed? How is this proposal different than the Clean Power Plan?

JM: In this new rulemaking, the EPA has proposed carbon pollution standards for existing coal-fired power plants, new gas-fired power plants, and a subset of existing gas-fired power plants. The standards range in magnitude of emission reductions required—and when those reductions must be achieved—depending on the type of plant as well as how frequently the facility runs and how long it intends to remain operating. For example, the EPA is proposing to require that any coal-fired power plant intending to operate past 2039 must limit its carbon emissions beginning in 2030 based on a facility using 90 percent carbon capture. For large, frequently used gas-fired power plants, the agency is proposing facility emission limits based on 90 percent carbon capture in 2035 or blending an increasing amount of hydrogen in place of gas over a slightly longer period.

The major difference between this proposal and the Clean Power Plan relates to how EPA determined the level of achievable emissions reductions, which is what tripped up the Clean Power Plan in the courts. The Clean Power Plan factored in plants shifting electricity generation from higher polluting sources to cleaner energy sources—from coal to renewables, for example—in how it set its emission reduction requirements. However, the court determined that basing such a determination on generation shifting required clear congressional authorization. As a result, these new standards only consider facility-specific pollution controls, such as installing carbon capture equipment or burning lower-carbon fuels with higher-carbon fuels, like hydrogen with fossil gas.

The proposed standards would be a major step forward in reducing carbon emissions from coal- and gas-fired power plants, but they don’t go far enough. The proposal covers what would be just 14 percent of existing gas-fired power plant capacity in 2035, has weak requirements for certain new gas-fired power plants, and includes compliance timeframes that stretch too far out into the future. Those provisions will need to be strengthened before the rule is finalized.

EN: How feasible will it be for power plants to capture their carbon emissions or, in the case of gas plants, switch to something like “green” hydrogen, which doesn’t emit carbon?

JM: An interesting, and critically important, aspect of Section 111 of the Clean Air Act—the source of EPA’s authority for this rulemaking—is that while the agency sets emission reduction requirements based on the “best system of emission reduction” that has been adequately demonstrated, states and utilities have wide latitude in the technologies and approaches they can employ to comply with those requirements.

That means there are really two different questions when you ask about “feasibility.” First, what adequately demonstrated technologies can the EPA cite that would result in the biggest emission reductions possible, considering cost and other factors? Second, when states act to comply with those emission standards, do the same technologies the agency relied on to derive the standards make sense, or are there other, superior technologies or approaches—including ones not available to EPA in its evaluation due to the constraints imposed on the agency by West Virginia v. EPA?

The onus is on the EPA to establish that the technologies it considers in setting its standards, such as carbon capture or hydrogen co-firing, are achievable. In the proposed rule, the agency included a recitation of anticipated costs, expected performance, and example projects on this front.

But the calculus changes when it comes to compliance. States may determine that even if a technology such as carbon capture has been adequately demonstrated for EPA’s purposes, it may still result in health, environmental, safety, and other risks that make it less preferable to an alternative compliance approach that would achieve the same level of emissions reductions, such as retiring a coal-fired power plant and replacing it with renewables instead.

The Union of Concerned Scientists maintains that when clean energy technologies go head-to-head with the various facility-specific options to reduce coal- and gas-fired power plants’ carbon emissions, such as hydrogen co-firing or carbon capture and sequestration, clean energy technologies will overwhelmingly win the day.

EN: Not only would the proposed standards cut carbon emissions, they also would significantly reduce toxic pollution, no?

JM: That’s right. Fossil fuel-fired power plants spew out all types of pollutants, not just carbon dioxide and methane, and they are extremely harmful to public health. The less we rely on these facilities, the less of these pollutants there’ll be.

The EPA estimates that, over the next two decades, the proposed new standards for coal-fired power plants and new gas-fired power plants will result in significantly lower emissions of fine particulate matter, sulfur dioxide, and nitrogen oxides. When the resulting public health benefits are combined with climate benefits, the EPA projects this provision of the new standards would result in a total annual net benefit of $5.4 billion to $5.9 billion. When translating these pollution reductions into health outcomes, the agency projects that in 2030 alone these reductions could result in approximately 1,300 avoided premature deaths, more than 2,000 avoided cases of asthma onset, 38,000 avoided school absences, and 66,000 avoided lost work days.

Keep in mind, those numbers do not include reductions anticipated from standards for existing gas-fired power plants, which will drive these numbers even higher. Furthermore, if states and utilities end up complying with EPA’s standards using clean energy, we can reasonably anticipate that the public health benefits will be even greater given the full pivot away from fossil fuels.

EN: How will the proposed standards protect fenceline communities that bear the brunt of power plant pollution?

JM: This is a critical concern. The fact is, for decades, people living in the shadow of fossil fuel-fired power plants—as well as in the vicinity of facilities that extract the fuels as well as pipelines, trains, and trucks that transport them—have been disproportionately harmed by air and water pollution. Given these communities are often disadvantaged, these harms have steadily perpetuated environmental injustices.

The EPA’s proposed standards will play a major role in the fate and future of fossil fuel-fired facilities, so community concerns must be front and center. The proposed standards stipulate that states must engage with communities when planning for compliance, but there’s room for these requirements to be stronger, and for the EPA—as well as other federal agencies—to incorporate more community protections and safeguards related to new infrastructure deployment. States also must fully consider the costs and risks to these communities from compliance pathways that rely on continuing fossil fuel use—even if smokestack carbon emissions decline—compared to switching to clean resources instead.

EN: Finally, what can the general public do to make sure the EPA finalizes the best possible version of these standards and they are not—like the Clean Power Plan—blocked by the fossil fuel industry?

JM: Great question. As important as these proposed standards are, they are just a proposal, and they will require a groundswell of public support to enable the EPA to finalize the strongest possible version by, among other things, closing polluter loopholes and requiring much faster timelines. It will be critical for the general public to weigh in with comments supporting the new standards and calling for the EPA to strengthen them, which they can do here.

The standards also will need strong public support to stand up to an onslaught of fossil fuel industry attacks. The industry has already disseminated disinformation about the rules, and the same fossil fuel-friendly interests that challenged the Clean Power Plan are signaling their intention to take the EPA to court again over the new standards.

As mentioned before, the EPA has not only the authority, but also the obligation, to regulate power plant carbon pollution. And yet, decades in the making, there are still no carbon pollution standards in place. We need all the public power we can amass to overcome the fossil fuel industry’s delaying tactics and see these standards through.