The Affordable Clean Energy (ACE) rule, the Trump administration's recently released substitute for his predecessor's Clean Power Plan (CPP), has been widely criticized as an ineffectual mechanism for addressing power plants' greenhouse gas (GHG) emissions. More broadly, the rule substitutes a technocratic, plant-by-plant approach for the more comprehensive and participatory state planning required by the now-repealed CPP.
The ACE identifies a range of potential heat-rate improvements (usually efficiency improvements) at coal-fired power plants and then lets the states determine which of these "candidate technologies" are feasible at which plants. The states then embody these performance requirements in state implementation plans (SIPs) subject to EPA approval. Energy system planning plays no role in controlling emissions.
In contrast, the CPP, formally repealed at the same time as the ACE was finalized, set the stage for state-level energy system planning. Under the CPP, utilities or plant owners could not only invest in plant-specific efficiency upgrades that would reduce the emissions per unit of energy created; they could also shift generation from coal-fired plants to less-polluting natural gas plants, and they could invest in zero-emission renewable energy. In a multi-step process that took into account the electricity options in each state, EPA indicated the emission performance goal each state should meet, and states were required to develop SIPs that showed how they would meet that goal. In their planning process, states could evaluate and choose how to meet the goal, whether through the strategies EPA used to set the goal or through other emission-reduction measures, like enhanced energy efficiency.
In a recent CPRBlog post, my CPR colleague Hannah Wiseman focused on ACE's decreased emission reduction ambitions. Here, I address another key difference between the CPP and the ACE: the advantages of the CPP's comprehensive state-level planning process in comparison with the ACE's minimalist technical fixes.
The first advantage is the way in which the CPP facilitated much-needed coordination between environmental regulators, on the one hand, and utility commissions, on the other. Together, these agencies could consider how facility controls and generation choices could combine to achieve the goals EPA had set for each state. Power plant emissions are inherently a function of emission controls, the purview of environmental regulators, as well as generation choices, the purview of state policymakers. The CPP SIP development process triggered unprecedented engagement between these formerly disparate wings of state government. The interagency coordination and state planning processes could have enabled more comprehensive and well-integrated environmental and energy strategies.
A second advantage follows. In many parts of the country, coal-fired power plant emissions contribute significantly to public health-threatening pollutants, including those that contribute to ozone (smog), fine particulates, and acid rain. Under the CPP, EPA encouraged states to take a multipollutant approach to reducing emissions. In other words, as states developed their SIPs for achieving CPP reductions, including switching generation from heavily polluting coal, they could consider choices that would maximize co-pollutant reduction benefits.
For example, they might choose to require the closure or decreased operation of coal-fired power plants in areas experiencing heavy pollution burdens, so as to maximize the multipollutant benefits of their strategy. Under the ACE, in contrast, EPA would not approve these measures because they don't qualify as "operational standards" on specific plants. By limiting the ability to develop a plan that integrates generation and control decisions, the ACE dampens state incentives to craft the measures most likely to solve multiple environmental challenges.
Another key attribute of an integrated state planning process is the opportunity for public participation in state decisionmaking over fundamental energy choices with wide-ranging implications. In particular, the CPP required states to create opportunities for meaningful engagement by traditionally disadvantaged communities, an important environmental justice objective. The CPP preamble states that "EPA envisions meaningful engagement to include outreach to vulnerable communities, sharing information and soliciting input on state plan development …." The ACE barely mentions public participation. Revised regulations for the relevant statutory provision require "one or more public hearings" on state SIPs, and states retain the option of cancelling the hearing if, after providing notice of a hearing option, no one requests one.
The CPP had its issues, including state targets that underestimated the emission reduction options available to the states and a convoluted methodology for determining appropriate state obligations. Nonetheless, the CPP's participatory state planning approach provided a much more robust process for envisioning ways to revamp our existing electricity system and reduce emissions from power plants, the nation's largest stationary source of carbon emissions. Moreover, although the CPP did not itself attempt to achieve decarbonization, its approach provided a stepping stone to the kind of strategic thinking necessary for the next essential stage: transitioning to a clean grid. The ACE, in contrast, operates in a vacuum and fails to position the states or the power sector for a greener and safer future.