Air pollution from electricity utilities in the USA

In the USA, SO2 emissions have reduced over the past 20 years due to the large-scale application of flue-gas desulfurization technology (FDG). In the decade 1994-2004 electricity generation from coal increased, but the use of lower sulphur content coal permitted a reduction by 79% in the SO2 emissions (11.7 Mt). However, in the decade 2004-214 the coal used had a higher sulphur content (subbituminous and lignite coals) so SO2 per kWh increases offset the fact that coal-powered electricity production decreased. The shift in coal quality added 2% to the sector’s SO2 burden.

PeriodAvg. SO2 emissions from electric utilities (US) /Mt
Source: EIA, 2015a, 2016b, From graph in article by M.A.Brown et al.,The Electricity Journal 30(2017)

The power sector in the USA accounts for 64% of SO2 emissions. SO2 damages human health, ecosystems, crops, timber production, and the built environment (acid rain). The cost to the US economy from SO2 range from 71 to 223 billion dollar every year.

(NRC 2010, Jaramillo and Muller 2016).

SO2 and NOx emissions are regulated by the US Clean Air Act Amendments 1990. The act sets limits on emissions from power plants, renewable portfolio standards, and federal energy efficiency standards on end-use equipment.

Electricity generation has remained fairly stable. In 1994, about 3,200 TWh (3.2 billion MWh) rose gradually and consistently to a peak of 4,100 TWh (4.1 billion MWh) generated in 2007, where it has remained with only slight fluctuations. The share of coal in electricity generation showed a similar growth from 1.7 billion MWh in 1994, to a plateau from 2000-2008 at just under or on 2.0 billion MWh, after which it has fallen unevenly to the 1.7 billion MWh mark again by 2014. A clearer trend is visible in the consistently falling percentage of coal in the energy mix from 1992 at 52% to the 2014 38%.