U.S. sulfur dioxide emission reductions: Shifting factors and a carbon dioxide penalty

For more than 20 years, the large-scale application of flue gas desulfurization technology has been a dominant cause of SO2 emission reductions. From 1994-2004, electricity generation from coal increased, but the shift to low-sulfur coal eclipsed this. From 2004-2014, electricity generation from coal decreased, but a shift to higher-sulfur subbituminous and lignite coal overshadowed this. The shift in coal quality has also created a CO2 emissions penalty, representing 2% of the sector's total emissions in 2014.