Q832. What factors influenced the trend in emissions for power plants?
A832. Reported emissions from electricity production decreased significantly from 2011 to 2018, from 2,222 million metric tons (MMT) CO2e in 2011 to 1,815 MMT CO2e in 2018, a decrease of 18.3%. Reported emissions for 2017 declined by 4.1% from 2016. However, emissions increased by 0.8% in 2018, marking the first increase in emissions since 2014.
Over the time period of 2011 through 2018, national net generation of electricity remained fairly consistent with an increase of two percent. Meanwhile, GHG emissions per unit electricity production by electric power facilities decreased from 539.7 to 442.6 MT CO2e per thousand megawatt-hours, an 18% drop. Several factors contributed to this reduction in emissions per unit of electricity produced including the increased use of renewable energy sources and more efficient natural gas combined-cycle generators. In 2011, 42.3% of U.S. electricity was produced from coal and 24.7% from natural gas; but by 2018, 27.4% of electricity production was derived from coal and 35.1% from natural gas. Electricity generated from renewable energy results in no greenhouse gas emissions from power plants; and generation from natural gas, particularly in combined-cycle generators, produces lower greenhouse gas emissions per unit of electricity produced than generation from coal. The 2018 increase in emissions were primarily caused by continued economic growth and a warmer than normal summer that resulted in higher electricity usage for air conditioning.
 U.S. Energy Information Administration, Electric Power Monthly Table 1.1. Net Generation by Energy Source: Total (All Sectors), 2009-May 2019 (accessed July 28, 2019) at: https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_1_01
 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2016. U.S. Environmental Protection Agency. April 12, 2018. EPA 430-R-18-003. Available at: https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks-1990-2016
 U.S. Department of Energy, Environment Baseline, Volume 1: Greenhouse Gas Emissions from the U.S. Power Sector. Available at: https://energy.gov/sites/prod/files/2017/01/f34/Environment Baseline Vol. 1--Greenhouse Gas Emissions from the U.S. Power Sector.pdf
 U.S. Department of Energy, Today in Energy, U.S. Energy-Related CO2 Emissions Increased in 2018 But Will Likely Fall in 2019 and 2020, January 28, 2019. Available at: https://www.eia.gov/todayinenergy/detail.php?id=38133.