We need to close a mercury pollution loophole for lignite coal plants

(This post was co-authored by EDF attorney Richard Yates)

The Environmental Protection Agency is soon expected to update our national protections against mercury and other toxic pollution from coal-fired power plants – pollution that is extremely dangerous to human health and has been linked to brain damage in children.

EPA proposed strengthening the Mercury and Air Toxics Standards and closing a loophole for lignite coal and is expected to issue its final update soon. EDF has found that, even as we have made great progress in reducing mercury pollution overall, the lignite coal loophole leaves parts of the U.S. at especially high risk.

Mapping Big Mercury Polluters

[(i) The owner/operator of the Comanche plant in Colorado has announced its intention to retire unit 2 by 2025 and unit 3 by 2030; unit 1 retired in 2022. (ii) The owner/operator of the Sherburne County plant in Minnesota has announced its intention to retire unit 1 by 2025 and unit 3 by 2034; unit 2 retired in 2023. (iii) The owner/operator of the Cardinal plant in Ohio has announced its intention to retire unit 3 by 2028; units 1 and 2 have no scheduled retirement dates. (Data: EPA’s Clean Air Markets Program Data; EIA’s 2022 Form EIA-860 Data – Schedule 3)] 

Two years ago, EDF published a map of the top 30 mercury-polluting power plants in 2020 across the United States. We have now refreshed this map based on data from 2022, and you can see the results above.

Our updated map shows the 30 coal-fired electricity plants with the greatest mercury emissions across the United States in 2022. The map displays annual mercury emissions in pounds. The darker the shade of red and the larger the circle, the greater the total annual mercury emissions. (Note that the size of the circle corresponds to the quantity of emissions and not the geographical area affected by mercury pollution.)

Our analysis shows that the six highest-emitting plants are predominantly located in Texas and North Dakota:

  1. Coal Creek (ND)
  2. Oak Grove (TX)
  3. Martin Lake (TX)
  4. Antelope Valley (ND)
  5. James H. Miller Jr. (AL)
  6. Labadie (MO)

These six plants alone emitted 1,442 pounds of mercury in 2022, accounting for almost half of the total mercury emitted by the top 30 plants. Closing the “lignite loophole” would drastically reduce these emissions since the four highest emitting plants all burn lignite coal. (Read more about lignite and the “lignite loophole” below)

The dangers of mercury pollution

Mercury pollution from coal-burning power plants impairs the brain development of young children and is linked to deadly heart attacks and hypertension in adults.

The most common way humans are exposed to mercury is through eating fish and shellfish. Mercury pollution in the air falls into our aquatic ecosystems and forms methylmercury, which is absorbed by small fish. Bigger fish eat the smaller fish, and the methylmercury becomes more concentrated as it travels up the food chain. (To find out more about mercury levels in seafood in your region, visit EPA’s Guidelines for Eating Fish that Contain Mercury, which contains links to FDA and state and local resources.)

As children’s brains rapidly develop during growth, they are especially susceptible to brain damage caused by methylmercury. Others at high risk include those located closest to power plants, people with existing health conditions, and people who rely on subsistence fishing – often in low-income communities and communities of color. A series of insightful interviews conducted by Moms Clean Air Force with members of the Muckleshoot Indian Tribe of Washington, the Ojibwe Nations in Minnesota, and the Menominee Nation in Wisconsin and upper Michigan has firsthand accounts of the harms of mercury poisoning to Native American food and culture.

More than a decade ago, EPA adopted the Mercury and Air Toxics Standards – nationwide limits on the pollution discharged from coal plants. These protections have proven tremendously successful. A white paper by the Harvard T.H. Chan School of Public Health found that the reduction in power plant mercury emissions from just the first eight years the Mercury and Air Toxics Standards were in effect resulted in 160,000 fewer deaths from cardiovascular diseases. What’s more, the reductions in mercury pollution were achieved at a fraction of the cost originally predicted.

What is lignite coal?

Lignite coal is one of the dirtiest types of coal burned at power plants to generate electricity. Not only does burning lignite produce high levels of mercury and other hazardous air pollution, but more lignite fuel must be burned to generate power compared to other types of coal – which produces even greater amounts of pollution.

In spite of that, lignite coal plants are subject to much weaker protections than plants that burn other types of coal. This weak standard, “the lignite loophole,” allows lignite plants to emit more than three times the mercury pollution of other coal plants (4 pounds per trillion British thermal units (lb/TBtu) vs. 1.2 lb/TBtu).

Lignite coal has a high moisture content that makes it unsuitable for shipping, meaning that it is often burned where it is mined. Texas and North Dakota contain the most extensive lignite deposits in the U.S.

Texas and North Dakota have 12 of the top 30 polluting plants on our map – and 10 of those 12 burn lignite coal. Also, EPA found that some coal plants in Texas have taken advantage of the “lignite loophole” by claiming to be subject to the less stringent mercury requirements despite burning less than one-percent lignite coal.

Reducing mercury pollution is feasible, cost-effective, and necessary

Requiring lignite coal plants to meet the same mercury pollution limits as other plants would provide a 70% reduction in mercury emissions from lignite plants. And advances in various control technologies make those reductions both achievable and cost-effective for coal plant owners and operators.

Andover Technology Partners estimates that all existing lignite plants can reduce mercury emissions far beyond EPA’s proposal, by well over 90%, just by using the emission controls already installed at these facilities.

This is consistent with the long-term demonstrated cost-effectiveness of the Mercury and Air Toxics Standards. Since its inception in 2012, 70% of coal-fired capacity achieved the standards well ahead of time and the actual cost of compliance has been just a fraction of what companies originally estimated, as illustrated by the 2012 statements of power company CEOs briefing investors on the declining costs.

In addition to closing the lignite loophole, EDF is calling on EPA to strengthen the mercury standard for non-lignite coal plants. Cost-effective and technologically feasible control solutions are also readily available for these plants. We have also recommended additional measures to safeguard people and communities, including continuous emissions monitoring requirements to provide more accurate information about toxics, and strengthened standards for metallic hazardous air pollutants like lead and arsenic.

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