Reduced emissions of CO2, NOx, and SO2 from U.S. power plants owing to switch from coal to natural gas with combined cycle technology

• Published in: Earth's future Vol. 2; no. 2; pp. 75 - 82
• Main Authors: de Gouw, J. A., Parrish, D. D., Frost, G. J., Trainer, M.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA Wiley Periodicals, Inc 01.02.2014; John Wiley & Sons, Inc
• Subjects: CO2 emissions; coal power plants; Electric power; electric power generation; Electric utilities; Emissions; Gases; Industrial plant emissions; Natural gas; natural gas power plants; NOx emissions; Power plants; SO2 emissions; VOCs; Volatile organic compounds
• ISSN: 2328-4277; 2328-4277
• DOI: 10.1002/2013EF000196

Since 1997, an increasing fraction of electric power has been generated from natural gas in the United States. Here we use data from continuous emission monitoring systems (CEMS), which measure emissions at the stack of most U.S. electric power generation units, to investigate how this switch affected the emissions of CO2, NOx, and SO2. Per unit of energy produced, natural gas power plants equipped with combined cycle technology emit on an average 44% of the CO2 compared with coal power plants. As a result of the increased use of natural gas, CO2 emissions from U.S. fossil‐fuel power plants were 23% lower in 2012 than they would have been if coal had continued to provide the same fraction of electric power as in 1997. In addition, natural gas power plants with combined cycle technology emit less NOx and far less SO2 per unit of energy produced than coal power plants. Therefore, the increased use of natural gas has led to emission reductions of NOx (40%) and SO2 (44%), in addition to those obtained from the implementation of emission control systems on coal power plants. These benefits to air quality and climate should be weighed against the increase in emissions of methane, volatile organic compounds, and other trace gases that are associated with the production, processing, storage, and transport of natural gas. Key Points Adding natural gas power plants in the United States reduced CO2 emissions by 23% Concurrent reductions of NOx and SO2 emissions were 40% and 44%, respectively Natural gas has air quality and climate benefits over coal for power generation