Energy-related carbon dioxide (CO2) emissions in the United States declined 3% in 2019, and they might fall by 11% in 2020, according to the U.S. Energy Information Administration (EIA). In 2018, the emissions rose by 3%.
Total energy-related CO2 emissions in 2019 were about 150 million metric tons lower than in 2018. Nearly all of the decline can be attributed to the changing mix of fuels used to generate electricity.
The electric power sector accounted for nearly one-third of U.S. energy-related CO2 emissions in 2019. Only the transportation sector emitted more CO2. Within the electric power sector, emissions from coal fell by 15% in 2019, and emissions from natural gas rose by 7%.
U.S. electric power sector emissions have declined 33% from the peak in 2007 because less electricity has been generated from coal and more electricity has been generated from natural gas, which emits less CO2 when combusted, and non-carbon sources. U.S. total energy-related CO2 emissions have fallen 15% since the 2007 peak.
Nuclear and renewable sources of electricity generation that do not emit CO2 comprised a record 38% share of U.S. electricity generation in 2019. Much of this growth came from the continued construction of solar and wind capacity. The changes in the composition of electricity generation and improvements in energy efficiency have led to a decline in the total carbon intensity of electricity, which has fallen from 619 metric tons per megawatt-hour in 2005 to 408 metric tons per megawatt-hour in 2019.
U.S. CO2 emissions related to energy consumption in the residential and commercial sectors remained flat in 2019. CO2 emissions from the industrial sector increased by 1.1% because of increased industrial output. The transportation sector had a 0.2% decrease in emissions, breaking a six-year trend of rising emissions in the sector since 2012.
CO2 emissions in 2020 are expected to fall by 19% for coal, 13% for petroleum and 2% for natural gas. The changes can be attributed to the economic and behavioral effects the COVID-19 pandemic has had on energy consumption.
This year, responses to the pandemic, including working from home, travel restrictions, and businesses limiting operations or closing, have impacted U.S. energy consumption. In April, monthly U.S. energy consumption fell to a 30-year low and emissions declined to a record low as many parts of the country implemented measures to slow the spread of COVID.
Petroleum accounted for 45% of U.S. energy-related CO2 emissions in 2020, and most of the emissions were from the transportation sector. CO2 emissions from petroleum in the transportation sector fell to 102 million metric tons in April, the lowest monthly level since February 1983.
Natural gas accounted for about 36% of U.S. energy-related CO2 emissions in 2020. The electric power sector consumes more natural gas than any other sector. In 2020, the use of natural gas to generate electricity is expected to rise even though electricity consumption declined slightly.
Coal CO2 emissions in 2020 are expected to fall to the lowest annual level since 1973 and account for 19% of total energy-related emissions, or 4,597 million metric tons. Most coal is consumed in the electric power sector in the United States, and coal has lost market share to natural gas and renewables since reaching a peak in 2007.