The Obama administration adopted the Clean Power Plan to reduce power sector greenhouse gas emissions in line with its commitments under the Paris Agreement climate accord. The Clean Power Plan invoked Clean Air Act § 111(d)’s “Best System of Emissions Reductions” to require states to implement low-carbon electricity dispatch rules and emissions trading to reduce overall power sector emissions within each state.

But the Clean Power Plan was dead on arrival, as the Supreme Court took the unusual step of staying its implementation before the case challenging the plan even reached the Court. Judicial challenges to the Clean Power Plan were never resolved, as the Trump administration “Affordable Clean Energy“ (ACE) rule repealed the Clean Power Plan and implemented much weaker greenhouse gas controls--on a plant-by-plant basis.

Now, the DC Circuit has thrown out the ACE rule in American Lung Association v. E.P.A., issued on January 19. While the decision initially appeared to raise the prospect that the Clean Power Plan would rise from the dead by operation of law, the new administration immediately moved to stay the issuance of the mandate to the extent that the mandate would reinstate the Clean Power Plan. EPA preferred a remand to the agency to formulate a replacement for the ACE rule, presumably one that would reflect the new administration’s goals and priorities – including a zero carbon energy electric grid nationwide by 2035.

The Clean Power Plan was bit of both an overreach and an underreach. By regulating power plant emissions “beyond the fenceline,” the CPP pushed the boundaries of the nature of regulations contemplated by § 111(d). Although the D.C. Circuit’s American Lung Association opinion specifically endorsed the “beyond the fenceline” approach as consistent with the plain language of §111d), the Supreme Court’s stay order was an ominous portent for that interpretation’s ultimate success. Yet the CPP was also an underreach – its modest goals, though consistent with the US Paris Agreement pledges, were far short of what was needed to put the U.S. on track to reach the Paris Agreement goal of limiting global warming to 1.5 degrees C. In fact, EPA’s motion to stay the resurrection of the CPP points out that the U.S. achieved the 32% 2030 carbon reduction goals of the CPP (compared to 2005) by 2019 – even though the plan never went into effect. In other words, even if implemented, the Clean Power Plan would not have achieved any reductions that were not already in the cards.

EPA’s request for a remand to develop a new set of § 111(d) power sector rules may indicate that this section of the Clean Air Act remains EPA’s implementation tool of choice. Presumably, EPA could avoid some of the litigation risk (and advance its zero emission goals) by adopting category by category-based emissions controls for thermal power plants – staying “within the fenceline.” In theory, at least, a zero emissions standard may be less of a statutory stretch than the grid-wide low-carbon dispatch rules of the Clean Power Plan. Nevertheless, several risks remain for invoking § 111(d) as a zero emissions pathway. These risks include the following:

1. Section 111(d) is a technology-based approach, and EPA must identify a technology capable of meeting the zero emissions standard. Not even carbon capture claims 100% carbon removal efficiency, and carbon capture and storage (“CCS”) has not proven economically viable at any existing power generation facilities.
2. Section 111(d) requires explicit consideration of cost, and EPA would have to be prepared to defend imposing the cost of CCS technology that would almost certainly render every coal fired power plant left in the country uneconomical, and possibly all of the gas fired plants as well.
3. Section 111(d) also has a potential preemption trap – the codified version states that §111(d) cannot be applied to source categories subject to air toxics regulation under § 112 (as coal-fired power plants are). There is a fascinating story of possible clerical error behind this, but no space to discuss it here. Part II of Judge Walker’s dissent in American Lung Association v. EPA has a full discussion and concludes that § 111(d) cannot be invoked to regulate coal fired power plants.
4. As the ACE rule itself demonstrated, whatever can be done under § 111(d) can be undone by the next, less climate friendly administration.

These risks lead this author to conclude that a more durable regulatory approach would be for EPA to bite the bullet and designate GHGs as criteria pollutants subject to National Ambient Air Quality Standards. According to Supreme Court precedent, NAAQS implementation need consider neither cost nor technical feasibility. And some of the NAAQS implementation horribles might be avoided by adopting only a secondary NAAQS for GHGs, as suggested here.