Figure 4.

Scenario comparison of air pollutant emissions for transitioning to BEBs (measured in million metric tons). The left side shows the emission of CO on a different scale from the rest of the emissions shown on the right. The only pollutant to increase under these scenarios is SO_x, which is mostly associated with coal-fired electricity generation, which continues to decline as a share of electricity generation. Bistline et al. project that NO_x emissions from electricity will decrease by 62% (range of 42–82%) and SO_x emissions will decrease by 73% (range of 49–94%) by 2035. The transition scenarios of Natural PhaseOut, 5% Yearly, and Top 100 show that if SO_x emissions are able to decrease quickly, there can still be some SO_x mitigation over the 14-year analysis period. As the electricity and industrial systems transition to net-zero emissions, SO_x emissions will continue to decline. Understanding the local changes and impacts of SO_x emissions under rapid electrification and decarbonization across power, transport, and industry is an important topic for future research.