Phasing out coal power plants based on cumulative air pollution impact and equity objectives in net zero energy system transitions

Transitioning to a net zero economy entails rapidly retiring US coal power plants, a major source of both greenhouse gases and air pollution. Conceptualizations of just transitions often embed climate, socioeconomic, and environmental justice objectives. Here we evaluate the influence of cumulative air pollution impact and equity objectives in the context of coal electric power plant retirement decisions. Operating coal power plants accounted for approximately 11 600 mortalities ($100B in damages) in 2018, disproportionately impacting low income, nonwhite, and rural populations. To evaluate the future phase-out of coal generators, we optimize for alternative climate policy goals, in addition to air pollution objectives related to the distribution of impacts on the basis of income, race, voting patterns, population density, and National Ambient Air Quality Standards classifications. With policy goals to both achieve net zero emissions by mid-century and to minimize cumulative air pollution-related mortality, approximately 134 000 deaths ($1.2T) are avoided from 2020 to 2050 (relative to business-as-usual). We find that the way in which equity objectives are operationalized has a large influence on asset-level retirement decisions and policy design. Phase-out strategies associated with policy objectives to minimize cumulative mortalities across the US population are generally consistent with objectives to minimize impacts on vulnerable subpopulations, but differ from those that target geographically-defined vulnerable communities.