EPA: Long-Term Trends Show Significant Reductions in Power Sector Emissions

(Credit: EPA)

The U.S. Environmental Protection Agency (EPA) recently released its annual data on power plant emissions for the year 2022 in the lower 48 states. Despite a 2% increase in electricity demand for these power plants (and a 3% increase for all electric generation in the first 11 months of 2022), emissions decreased from 2021. This reduction is primarily due to changes in the mix of fuels used in electricity generation, which reflects the long-standing trend of decreasing annual emissions. The 2022 data indicated a 6% decrease in coal generation and a 7% increase in natural gas generation from 2021.

Michael Regan, EPA Administrator, emphasized the importance of protecting communities living near power plants from environmental and health hazards. While the data indicate progress, there is still work to be done. The EPA will continue to collaborate with state, tribal, and local leaders, as well as major players in the private sector, to protect public health.

2022 data revealed a 4% decrease in nitrogen oxide (NOX) emissions, a 10% decrease in sulfur dioxide (SO2) emissions, a 1% decrease in carbon dioxide (CO2) emissions, and a 3% decrease in mercury emissions compared to 2021. Additionally, NOX emissions during the ozone season (May 1 to September 30) decreased by 10%. Notably, ozone season NOX emissions fell by 21% in states covered by the current Cross-State Air Pollution Rule (CSAPR), which requires additional NOX emission reductions to facilitate the attainment of the 2008 National Ambient Air Quality Standards.

The Final Revised Cross-State Air Pollution Rule Update is a set of regulations aimed at reducing air pollution that crosses state lines in the United States. The update, which was finalized in 2021, requires 12 states in the eastern part of the country to reduce emissions of sulfur dioxide and nitrogen oxides, which can contribute to smog and acid rain. The rule also includes a new trading program that allows states to buy and sell pollution credits, giving them flexibility in meeting their emission targets. The EPA estimates that the rule will result in significant health benefits by reducing premature deaths, asthma attacks, and other respiratory problems.

Thirty-Two Year Decline

Since 1990, power plant emissions of SO2 have declined by 93%, and NOX emissions have decreased by 87%. In 2022, sources in both the CSAPR annual program and the Acid Rain Program (ARP) emitted 0.85 million tons of SO2, a decrease of 11 million tons from 1995 levels. Similarly, sources in these programs released 0.75 million tons of NOX in 2022, a reduction of 5.1 million tons from 1995 levels. While complying with programs to reduce SO2, NOX, and mercury, power plants have reduced their CO2 emissions by 22% between 1995 and 2022.

Power Plant Emissions & Public Health

The significant decrease in power sector emissions over the long term has resulted in a considerable reduction in air pollution, which has helped protect public health. NOX and SO2 emissions contribute to the formation of ground-level ozone and particulate matter, which can lead to respiratory and cardiovascular problems. Exposure to mercury, a toxic metal that can accumulate in the food chain and end up in fish and shellfish can have adverse effects on the nervous systems of infants and children, impairing their growth and development. Additionally, mercury exposure can affect the cardiovascular function and central nervous system of adults.

NOx and SO2 emissions:

• Diesel trucks and buses are a significant source of NOx emissions.
• In urban areas with high levels of NOx and SO2, the emissions can react with sunlight to form ground-level ozone and particulate matter.
• Exposure to these pollutants can lead to respiratory problems such as asthma, bronchitis, and emphysema, as well as cardiovascular problems such as heart attacks and strokes.

Mercury exposure:

• Minamata Bay disaster occurred in Japan in the 1950s and 60s, but the full extent of the contamination and its effects were not fully recognized until the 2000s. The disaster was caused by industrial wastewater containing mercury being discharged into the bay, leading to widespread mercury poisoning in the local population. Thousands of people suffered from neurological and physical symptoms, and many died.
• In the early 2000s, there were growing concerns about mercury contamination in seafood, particularly tuna, and swordfish. The U.S. Food and Drug Administration (FDA) issued advisories for pregnant women and young children to limit their consumption of certain types of fish due to the potential risk of mercury exposure.