From coal to natural gas for electricity generation in the US

Between 2005 and 2016, 334 coal-fired power units at 138 facilities were shut and 612 new natural gas-fired units across 243 facilities came online in the United States. A small fraction of the natural gas units were upgraded, whereby a new gas-fired unit replaced an older one, but the majority were new units that were added to existing facilities or new facilities entirely.

Shifting from coal to natural gas was shown to have resulted in reductions in all-cause mortality. These estimates represent impacts from the pathways related to reductions in air pollutants (i.e. circulatory and respiratory pathways), in addition to impacts of O₃ and other stack-related co-emissions. Crop yield estimates represent impacts from the effects of aerosols on radiation, temperature and precipitation, in addition to direct deposition on the crops, as well as plant damage caused by O₃ and O₃ precursors (e.g. NOx and volatile organic compounds).

A reduction of 470 million tons of CO₂ between 2006 and 2016, equating to 47 million tons annually.

From 2006 to 2016, the decommissioning of 334 coal-fired units resulted in reductions in PM2.5, NO₂ (reduction of 2.25 million tons), SO₂ (reduction of 7.95 million tons), and O₃. Lower aerosol and O₃ concentrations also showed benefits to crop productivity. With each unit decommissioning, counties where a coal-fired unit was taken offline in their immediate vicinity showed an average of 0.18% (range between 0.01 to 0.35%) reduction in total all-cause mortality rate (deaths from all causes).

These changes resulted in a total of 22,563 (range between 16,896 to 43,428) lives saved, particularly among the elderly. With each unit that was decommissioned corn yield also increased by 1.1% (range between 0.56 to 1.63%), equating to a total of 329 million (range between 169 to 490 million) bushels of corn produced during that time period.

In 2021, 23% of electricity generated in the US was from coal, with 234 coal power plants still operational across the country. Decommissioning these remaining units would save over 14 million tons of CO₂ annually (Carbon Brief, 2019). It is important to note, however, that this study has shown benefits from decommissioning older coal-fired units, but the newer natural gas units are not entirely harmless. Natural gas units are associated with higher than baseline average pollutant concentrations (not in comparison with coal), and have a different pollutant mix, for example, new natural gas-fired units are associated with higher than baseline average of PM2.5 levels at local levels, as well as higher than baseline average O₃ levels at the county level.