The U.S. Environmental Protection Agency (EPA) released publicly available, annual data on 2021 emissions of nitrogen oxides (NO_X), sulfur dioxide (SO₂), carbon dioxide (CO₂), and mercury from power plants in the lower 48 states. Emissions in 2021 were higher than 2020, reflecting a rebound in coal-fired generation as natural gas prices and energy demand increased. However, compared to 2019, 2021 emissions fell between 3% and 11%, reflecting the long-standing trend of decreasing annual emissions. 

Compared to 2020, the 2021 data show a 6% increase in NOx emissions, a 20% increase in SO₂  emissions, a 7% increase in CO₂ emissions, and a 13% increase in mercury emissions. Additionally, ozone season (May 1 to September 30) NO_X  emissions increased by 5%. Overall, based on the first 11 months of 2021, electricity demand increased by 3% compared to 2020.

Long-term declines in emissions are due primarily to changes in the mix of fuels used in electricity generation. While data from 2021 showed a one-year 16% increase in coal generation and a 3% decrease in natural gas generation, there is a shift underway from higher emitting to lower and zero emitting generation.

EPA collects detailed SO2, NOX, CO2, and mercury emission data and other information from power plants across the country, as part of ARP, the CSAPR Programs, and the Mercury and Air Toxics Standards (MATS). Emissions data collected through these programs are posted online and accessible to the public in summary form. 

To find out more about how to save money on emission testing required for Power Plants, including the Acid Rain Program, Cross-State Air Pollution Rule (CSAPR and RCU) and Mercury and Air Toxics Standards (MATS) contact ESS.