Since 1990, our emissions of sulfur dioxide and nitrogen oxides are down over 80 percent, while electricity generation has increased about 30 percent to serve growing demand. Performance »
Through 2012, Southern Company:
Southern Company participates in data collection and research studies. Two leading studies, SEARCH and ARIES, have provided an empirical foundation for air quality policy, practices, and emerging issues.
SEARCH monitors the relationship of myriad compounds comprising particulate matter to health effects. ARIES investigates associations between specific air pollution components and human health.
Together, this ongoing research provides data to help establish causal relationships between chemicals in the air and their effects on people, and ultimately air quality standards to safeguard human health.
At the end of 2011, Southern Company installed and is operating scrubbers at 17 and SCRs at 16 of its coal units. An additional three scrubbers and four SCRs are under construction. Baghouses are operating at four units.
Emissions from burning coal contain sulfur dioxide. The scrubber sprays the combustion emissions with a water and limestone mixture. The sulfur dioxide reacts with the limestone to form gypsum, a reusable compound. The clean gas rises out of the stack. This system removes up to 95 percent of the sulfur dioxide.
SCRs remove up to 85 percent of nitrogen oxides, another emission from burning coal. An SCR, or selective catalytic reduction system, adds ammonia to the gases exiting the boiler. A catalyzed chemical reaction breaks the nitrogen oxides down to harmless nitrogen and water. Catalytic converters in autos are similar devices.
Baghouses collect fly ash and other particulate matter. Baghouses work like vacuum cleaners, forcing the flue gas through filter bags, which collect more than 99 percent of the dust particles.
Devices like SCRs, scrubbers, and baghouses require energy to operate. Typically emission-control devices reduce generation by about 2.5 percent.