Which technology is primarily used to reduce SO2 emissions from coal-burning power plants?

The technology primarily used to reduce sulfur dioxide (SO2) emissions from coal-burning power plants is wet-scrubber units. These systems work by spraying a liquid solution, typically a mixture of water and a chemical reagent like limestone, into the flue gas stream. As the flue gas passes through the scrubber, the SO2 reacts with the chemicals in the liquid, converting it into a solid form that can be removed from the gas stream. This method effectively captures a substantial portion of SO2 emissions before they are released into the atmosphere, thereby helping to mitigate the environmental impact of coal combustion.

Other technologies listed, such as catalytic converters, ultrafine mechanical filters, and afterburners, primarily target different pollutants or operate under different principles. Catalytic converters are more commonly associated with reducing nitrogen oxides (NOx) and carbon monoxide (CO) in automotive applications, while afterburners are used to burn off excess hydrocarbons and improve combustion efficiency but are not specifically aimed at SO2 reduction. Ultrafine mechanical filters are generally used for particulate matter control rather than gaseous emissions. Thus, the wet-scrubber units are the most effective and widely adopted technology for managing sulfur dioxide emissions in coal-burning power plants.