Sulfuric acid mist, also known as H2SO4 or SO3, is one of the least publicized air pollutants associated with emissions from coal-fired power plants. Long overshadowed by nitrogen oxides, sulfur dioxide, and carbon dioxide, sulfuric acid mist is typically not emitted in the boundary-crossing and globe-altering quantities of the more frequently discussed air pollutants. In the whirlwind of the United States Environmental Protection Agency’s (EPA) recent air regulations of coal-fired power plants including the Mercury and Air Toxic Standards for power plants (MATS), the New Source Performance Standards and the Tailoring Rule for greenhouse gases, and the recently vacated Cross-State Air Pollution Rule, sulfuric acid mist has remained relatively untouched. But EPA’s regulations, which have imposed dramatic new emission limits on sulfur dioxide, nitrogen oxides, greenhouse gases, mercury, and hydrochloric acid, are likely to have a significant impact on sulfuric acid mist emission control strategies at coal-fired power plants.
Sulfuric acid mist emissions from coal-fired power plants, which creates tell-tale blue plumes (not pictured here), has increasingly been under scrutiny by the EPA over the past decade. Photo credit to ribarnica.