In general, the CO2 associated with natural gas supplied by local distribution companies (LDCs) varies due to fluctuations in weather, the relative price of natural gas compared to other fuels and the prevailing economic conditions. The annual CO2 reported for natural gas supplied by LDCs has ranged between a low of 709.5 million metric tons (MMT) in 2012 and a high of 822 MMT in 2019 and is directly proportional to the quantity of natural gas supplied. The natural gas supply has increased every year since 2012. This increase is primarily because of increased demand due to economic growth, relatively low natural gas prices due to high levels of natural gas production, and greater reliance on natural gas to fuel power plants. [1, 2] The increase in natural gas supplied by LDCs observed between 2018 and 2019 is primarily due to greater use of natural gas in the electric power sector. Natural gas supplied by LDCs to the electric power sector increased by 3 percent in 2019 compared with 2018. Natural gas supplied by LDCs to the residential, commercial and industrial sectors in 2019 changed only modestly from those reported in 2018, with increases of less than 1 percent for the residential and commercial sectors and a decrease of less than 1 percent for the industrial sector. The increase in natural gas consumed by the electric power sector is due in part to low gas prices and the retirement of coal-fired power plants. [2,3]
The reported CO2 for 2011 and 2012 are also affected by changes in the default emission factors. The default emission factor for natural gas supplied was revised in 2013 to a value about 1% less than the default emission factor used in years prior to 2013. For an LDC that uses the default emission factors, the total CO2 value reported in 2013 and subsequent years is 1% lower than would have been reported if the emission factor had not been updated. Since many LDCs use emission factors developed using their own data, the overall impact on CO2 for the sector is small. However, the total CO2 for the sector is lower for 2013 and subsequent years than would have been reported if the emission factor had remained unchanged.
[1] U.S. Department of Energy, Today in Energy, U.S. Natural Gas Production, Consumption, and Exports Set New Records in 2019, October 5, 2020. Available at: https://www.eia.gov/todayinenergy/detail.php?id=45377.
[2] U.S. Department of Energy, Today in Energy, In 2019, the United States Produced and Consumed Record Volumes of Natural Gas, July 10, 2020. Available at: https://www.eia.gov/todayinenergy/detail.php?id=44336.
[3] U.S. Department of Energy, Today in Energy, More than 100 Coal-fired Plants have been Replaced or Converted to Natural Gas Since 2011, August 5, 2020. Available at: https://www.eia.gov/todayinenergy/detail.php?id=44636.