U.S. Carbon Emissions Increase from Last Year, but Still 28% Less Than in 2005

A newly released update to the Power Sector Carbon Index, developed by Carnegie Mellon University with the support of Mitsubishi Hitachi Power Systems (MHPS), found that U.S. power plant emissions averaged 955 lb of CO2 per MWh during the first three months of 2017.




1. Carnegie Mellon University Power Sector Carbon Index.
The index shows that power sector carbon emissions have been on a steady decline for more than a decade. Emissions in the first quarter of 2005 were 1,331 lb/MWh. Courtesy: Scott Institute for Energy Innovation. (2017). Power Sector Carbon Index. Carnegie Mellon University, Pittsburgh, PA. Retrieved from https://www.emissionsindex.org.

Carbon emissions were slightly higher than during the same period last year, because coal-fired generation made up a greater portion of the power mix. Coal accounted for 292 million MWh in the first quarter this year, compared to 278 million MWh in the 2016 period. Natural gas–fired power generation declined about 16% year over year.

“Higher natural gas prices, lower overall electricity demand, and growth in renewable generation likely contributed to fewer natural gas MWh in the first quarter of 2017 compared to the first quarter of 2016,” Professor Inês Azevedo of Carnegie Mellon’s Department of Engineering and Public Policy said in a press release.

Other year-over-year changes included:

  • Total electricity generation decreased 2% in the first quarter of 2017 compared to the first quarter of 2016.
  • Coal generation carbon intensity decreased slightly in the first quarter of 2017 (2,241 lb CO2/MWh) compared to the first quarter of 2016 (2,252 lb CO2/MWh).
  • Natural gas generation carbon intensity increased about 2% in the first quarter of 2017 (923 lb CO2/MWh) compared to the first quarter of 2016 (908 lb CO2/MWh).
  • Renewable electricity generation swelled 9.7% in the first quarter of 2017 (184 million MWh) compared to the first quarter of 2016 (168 million MWh).
  • Nuclear electricity generation decreased 1% in the first quarter of 2017 (202 million MWh) compared to the first quarter of 2016 (204 million MWh). Nuclear represented 21% of total generation in the first quarter of 2017.

“This quarter, Carnegie Mellon showed that the carbon intensity benefit of more power generation from renewables was offset by an increase in coal-fired power plant dispatch and a corresponding decrease in natural gas power plant dispatch,” said Paul Browning, president and CEO of MHPS-Americas.

The Carnegie Mellon Power Sector Carbon Index provides a comprehensive picture of the carbon intensity of electricity production from 2001 to the present. The index also provides a summary of electricity generation produced from coal, natural gas, nuclear, and renewables.

Aaron Larson, executive editor (@AaronL_Power, @POWERmagazine)