Which technology is used to remove sulfur dioxide from coal-fired power plant flue gases?

• A. Baghouses
• B. Flue gas desulfurization (scrubbers)
• C. Catalytic converters
• D. Photocatalytic oxidation systems

Answer: (B)

Coal-fired power plants emit sulfur dioxide, a pollutant that contributes to acid rain. The technology used to remove it is flue gas desulfurization, commonly called a scrubber. In a wet scrubber, the hot flue gas passes through an alkaline slurry—usually limestone or lime—that absorbs the SO2. The absorbed gas reacts to form solid sulfates (like gypsum) which are then removed from the stream, greatly reducing SO2 emissions before the gas is released from the stack. This is why scrubbers are the go-to method for removing sulfur dioxide. Other devices target different pollutants: baghouses capture fly ash (particulates); catalytic converters reduce CO, hydrocarbons, and NOx in vehicle exhaust; photocatalytic systems are used mainly for organic pollutants.