For suppliers of natural gas liquids, the The CO₂ associated with natural gas liquids (NGLs) supplied to the U.S. economy (i.e., ethane, propane, butane, isobutane and pentanes plus) has gradually increased from 212 supply reported 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 2011 to 434 MMT in 2020. Except for a small decrease in 2013, the supply of NGLs has increased steadily every year with ethane and propane making up about 70 percent by volume of the NGLs supplied each year by U.S. fractionators. [1]The increase in NGL supply is due to increased production of natural gas in areas that are high in natural gas liquids; increased U.S. demand for NGL products; increased production capacity due to construction of new fractionation plants (124 plants in 2020 compared with 116 in 2011); and increased production at existing plants (ratio of CO₂ to number of plants increased from 2.6 MMTCO₂/plant in 2017 to 3.5 MMTCO₂ /plant in 2020); The year-over-year increases in the CO₂ emissions from NGLs were approximately 2012 and a high of 826.2 MMT in 2022 and is directly proportional to the quantity of natural gas supplied. The total volume of natural gas supplied increased by 10.2% in 2018 and by 0.6% in 2019. In 2020, natural gas supplied decreased by 5.8% percent, but rebounded slightly in 2021. However, the CO₂ reported in 2021 was 31.6 MMT lower than the 2019 high of 822.5 MMT. The increase in natural gas supplied in 2018 and 2019 was primarily due to economic growth, relatively low natural gas prices resulting from high levels of natural gas production, and greater reliance on natural gas to fuel power plants. [1, 2, 3] The lower annual CO₂ emissions reported for 2020 is due to a reduction in demand by residential, commercial (which includes restaurants, hotels, and schools), and industrial consumers. Natural gas supplied to residential, commercial, and industrial customers in 2020 decreased by 6.7 percent, 10.1 percent and 5.9 percent, respectively, compared with 2019, despite the lower natural gas prices. [3] The decrease in natural gas consumption by residential users is likely due to milder winter weather in January - March 2020 and November – December 2020, while the lower consumption in the commercial and industrial sectors is likely caused by plant closures caused by the COVID-19 pandemic. [4] Natural gas consumption by the electric power sector increased by 4 percent in 2020. In 2022, natural gas consumption increased across all sectors, with the largest increases occurring in the commercial and residential sectors, where consumption increased by 6.7% and 5.2% respectively. [8]  

Increases in the residential and electricity sectors in 2022 were 5.2% and 7.9% respectively. [8] The average natural gas price for residential customers increased from $12.18 per thousand cubic feet in 2021 to $14.75 in 2022. [5] Natural gas consumption in the electricity sector has increased each year since 2018 and is due in part to low gas prices and the retirement of coal-fired power plants. Although natural gas consumption by the electricity sector decreased slightly in 2021.[8]. Natural gas consumption by the electricity sector grew by 19.3 million cubic feet in 2021 from the 49.7 million cubic feet consumed in 2020 and may be due to higher natural gas prices in 2021. The average natural gas price paid by power plants in 2021 was double the price in 2020. [2, 3, 5, 6, 7]. 12 percent for 2018 and 2019, and 8 percent for 2020. The increased NGL production reported in recent years is also partly due to increased exports due to the construction of new pipelines and export terminals. [2] Exports of propane have increased every year since 2012 due to strong market demand in Asia.[3] Ethane supply increased in 2019 in response to increased demand from new petrochemical facilities in the U.S. that use ethane as a feedstock. [4]

The reported CO₂ for 2011 and 2012 are also affected by changes in the default emission factors. For suppliers of natural gas liquids, The default emission factor for natural gas supplied was revised in 2013 to a value about 1% less than the default emission factors used for calculating the CO₂ for ethane, propane, butane and isobutene were revised in 2013. The default emission factors for propane, butane and isobutane were increased by a few percent over those used prior to 2013, while the default emission factor for ethane was decreased by over 30 percent. The impact these changes had on the total CO₂ reported by an NGL fractionator depends on the mixture of products the plant supplies and whether the fractionator used the default value or a measured value. Since most NGL fractionators supply ethane, the reported CO₂ across the industry was lower beginning in 2013 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 what 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 factors had not been updatedemission factor had remained unchanged.

[1]          U.S. Department of Energy, Today in Energy Information Administration, U.S. Energy Information Administration/Petroleum Supply Annual 2019, Volume 1, Table 15. Natural Gas Plant Net Production and Stocks of Petroleum Products by PAD and Refining Districts, 2019, August 31, 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]     petroleum/supply/annual/volume1/pdf/table15.pdf.[2]     U.S. Department of Energy, Today in Energy Information Administration, This Week in Petroleum, In 2020, Increased Propane, Other HGL Exports Contribute to Continued Strong Product Exports Despite Reductions in Major Transport Fuels, September 23, 2020. Available at: U.S. Natural Gas Prices were the Lowest in Decades, January 7, 2021. Available at: https://www.eia.gov/todayinenergy/detail.php?id=46376

[4]     U.S. Department of Energy, Today in Energy, U.S. Natural Gas Consumption was Lower in 2020 in All Sectors Except Electric Power, March 10, 2021. https://www.eia.gov/petroleum/weekly/archive/2020/200923/includes/analysis_print.phptodayinenergy/detail.php?id=47076

[5]     U.S. Department of Energy, U.S. Energy Information Administration, Monthly and Annual Natural Gas Prices. Available at https://www.eia.gov/dnav/ng/ng_pri_sum_dcu_nus_a.htm.

[6.[3]     U.S. Department of Energy, Today in Energy Information Administration, The United States Exported More Propane than Distillate in 2020, March 8, 2021. Available at: 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.

[7]     U.S. Department of Energy, Today in Energy, In the past 20 years, natural gas has displaced most coal-burning generation in Pennsylvania, January 26, 2023. Available at https://www.eia.gov/todayinenergy/detail.php?id=4703655319

[48]       U.S. Department of Energy, U.S. Energy Information Administration, Hydrocarbon Gas Liquids Explained, October 31, 2019Natural Gas Consumption by End Use. Available at : https://www.eia.gov/energyexplained/hydrocarbon-gas-liquids/prices-for-hydrocarbon-gas-liquids.phpdnav/ng/ng_cons_sum_dcu_nus_a.htm

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