Evaluating Multi-pollutant\nImpacts of Sulfur Reduction\nStrategies in the United States: A Cost-Benefit Approach

Electricity generation units (EGUs) emit a mix of health-\nand climate-relevant\nair emissions through coal combustion, with the potential to impact\nmultiple emissions. Previous studies have focused on evaluating the\ncobenefits of climate policies on air quality, studies that consider\nhow air pollution controls affect carbon emissions remain relatively\nsparse. To evaluate different emission reduction strategies’\nimpacts on multiple air pollutants and carbon dioxide (CO<sub>2</sub>), here we apply a multi-pollutant analysis framework, focused on\nsulfur dioxide (SO<sub>2</sub>) controls on coal-fired EGUs in the\nUnited States (U.S.). Eighty-nine EGUs without SO<sub>2</sub> controls\nin the contiguous U.S. as of 2020 are identified and investigated.\nResults show that add-on pollution controls like flue gas desulfurization\n(FGD) reduce SO<sub>2</sub> emissions from coal combustion, but increase\nemissions of nitrogen oxides (NOx), fine particulate matter (PM<sub>2.5</sub>), volatile organic compounds (VOCs), and CO<sub>2</sub>. A coal-to-natural gas transition reduces all pollutants except\nVOCs. A coal-to-renewable transition reduces all studied pollutants.\nWe find that add-on SO<sub>2</sub> controls could generate a total\nannual net benefit of $13.4 billion nationwide when considering a\nmulti-pollutant portfolio of emissions, as compared with $32.9 billion\ntotal annual net benefits from coal-to-natural gas transition and\n$40.5 billion from coal-to-renewable transition. Our results highlight\nthe potential of implementing the multi-pollutant analysis framework\nto evaluate multi-pollutant emission reduction strategies.