Flue-gas desulfurization

Before flue gas desulfurization was installed, the emissions from the Four Corners Generating Station in New Mexico contained a significant amount of sulfur dioxide.
The G. G. Allen Steam Station scrubber (North Carolina)

Flue-gas desulfurization (FGD) is a set of technologies used to remove sulfur dioxide (SO2) from exhaust flue gases of fossil-fuel power plants, and from the emissions of other sulfur oxide emitting processes such as waste incineration, petroleum refineries, cement and lime kilns.