Why marginal CO 2 emissions are not decreasing for US electricity: Estimates and implications for climate policy

Abstract

Significance Marginal emissions of CO 2 from the electricity sector are critical for evaluating many climate policies. We provide estimates of marginal CO 2 emissions for electricity use in the United States that vary by region, hour of day, and year to year. Despite a decrease in average emissions over the last decade, marginal emissions have increased. We apply our estimates to an analysis of the Biden administration’s target of having electric vehicles make up 50% of new vehicle purchases by 2030. We find that, without significant and concurrent changes to the electricity sector far more substantial than those over the last decade, the increase in electricity emissions is likely to offset more than half the emission reductions from having fewer gasoline-powered vehicles.