Mercury Emissions

Mercury pollution is a serious problem in Wisconsin and the United States; it threatens human health and harms ecosystems. While mercury pollution can come from a wide variety of sources, emissions into the air from coal power plants is the largest and most serious problem. The burning of coal accounts for over 50% of toxic mercury emissions into the air in the United States.[1]

The entire state of Wisconsin is under a fish consumption advisory because of high mercury levels in the fish in our waters. This is a serious issue in a state where our waters, and our fish, are key recreational and economic resources.

Key Points

  • Coal-fired power plants are the largest human-caused source of mercury emissions to the air in the United States, accounting for over 56 tons annually.[1]
  • In Wisconsin, over 4,000 pounds of mercury are emitted into the air every year from stationary pollution sources.[2]
  • Mercury pollution has both local and long-distance impacts: about 10% of all mercury discharged from a particular smokestack falls within 6 miles of that source and roughly 50% is deposited within 600 miles.[3]
  • With the new mercury emissions reduction rules in Wisconsin, mercury emissions from large power plants will be reduced by 90% to just 536 pounds of emissions annually as soon as 2015.[2]
Clean Wisconsin's Work

Clean Wisconsin strives to reduce harmful mercury emissions in our state and protect the water and fish resources that are so important to our economy and our heritage. Clean Wisconsin, along with hunting and fishing groups across the state, successfully petitioned the Department of Natural Resources in 2002 to make Wisconsin the second state in the nation to regulate mercury emissions from coal-fired power plants. In 2008, with the passing of Wisconsin’s Mercury Rule, Clean Wisconsin and our allies had another great victory and the state took a valuable step toward further protecting its air and water from toxic mercury emissions.

Clean Wisconsin continues to work to reduce mercury emissions in the state and promotes enforcement and monitoring of emission reductions by sources in our state.

Clean Wisconsin Media and Materials

 

Questions and Answers

Where do mercury emissions come from?

It is estimated that about two-thirds of all mercury emission in the world come from human sources. About half of this is direct emissions from processes such as burning coal. The other half is mercury that originally came from direct emissions, but later settled to the earth and is now being re-emitted by natural processes. The remaining one-third of global mercury emissions is estimated to come purely from natural processes like volcanoes.[4]

What are major sources of mercury emissions?

The largest source of direct mercury emissions is coal-fired power plants. Coal has a certain amount of mercury in it naturally, which is released into the air along with other emissions when it is burned. Other energy sources such as industrial boilers and electric arc furnaces also emit large amounts of mercury into the air. Other non-energy sources include processes such as burning of hazardous, municipal and medical waste; steel-making; and the industrial chlor-alkali production process.[5]

How do mercury emissions in the air get into our water and soil?

Mercury in the air contaminates land and water through a secondary process called deposition. Most commonly, airborne mercury attaches to water in the air and then comes down to earth with precipitation, called wet deposition. However, airborne mercury can also settle to the ground after attaching to other airborne particles or simply on its own due to gravity (dry deposition).

Since mercury is an element that doesn’t break down over time, it can be stored in the soil for decades. Recent estimates indicate that of the 200,000 tons of mercury emitted since 1890, about 95% still resides in soils.[3] Also see our Mercury Pollution Background page for more information.

How do mercury emissions harm the environment and threaten health?

Discussed in more detail on our Mercury Pollution Background page, toxic mercury pollution has many harmful effects on wildlife and is a significant threat to human health and development. After the deposition of mercury emissions to the earth, it can be converted by microorganisms into dangerous compounds such as toxic methylmercury, which contaminates fish. This methylmercury harms development, reproduction and other abilities in waterfowl and aquatic mammals. High concentrations of methylmercury in fish can also threaten human health and development, as people are exposed by consuming those fish.

Quick Facts
  • Coal-burning power plants are the largest human-caused source of mercury emissions to the air in the United States.[1]
  • Over 56 tons (or 112,000 pounds) of mercury are emitted each year from coal-fired power plants, accounting for over 50% of all human mercury emissions in the United States.[1]
  • In Wisconsin, over 4,000 pounds of mercury are emitted into the air every year from stationary pollution sources.[2]
  • Mercury pollution has both local and long-distance impacts: about 10% of all mercury discharged from a particular smokestack falls within 6 miles of that source, and roughly 50% is deposited within 600 miles.[3]
  • Other large sources of mercury emissions are industrial boilers (about 7% in the U.S.), burning hazardous waste (about 4%), and electric arc furnaces used in steel-making (also about 7%). [5]
  • Burning municipal and medical waste, as well as the chlor-alkali industrial process, were once large sources of emissions. New regulations, replacement of old technology and other mercury-reduction efforts have largely reduced mercury emissions from these sources. [5] [6]
  • An estimated 69 pounds of mercury, or 1.1% of total state air emissions, came from dental and laboratory use in 1996. [3]
Wisconsin Data, Trends, and Legislation

In Wisconsin, we produce most of our electricity through the burning of coal, which releases mercury into the atmosphere. This toxic mercury can bioaccumulate in ecosystems, especially aquatic systems with adverse affects on human and animal life. This is especially problematic in Wisconsin where much of our recreation, tourism and diet depend on fishing.[3]

  • Over 4,000 pounds of mercury were emitted from stationary sources in Wisconsin in 2005.[2]
  • Coal-fired utility power plants are by far the largest collective source of mercury air pollution in Wisconsin, accounting for about 40% of all mercury air pollution in the state annually.[3]
  • Wisconsin power plants alone have emitted over 2,700 pounds of toxic mercury into our air each year, making Wisconsin the 18th-largest mercury emitter from coal in the country.[7]
  • With the new mercury emissions reduction rules in Wisconsin, mercury emissions from large power plants will be reduced  by 90% to just 536 pounds of emissions annually as soon as 2015.[2]
  • The EPA’s proposed Mercury and Air Toxics Standards (MATS) will also help to reduce mercury emissions in Wisconsin and nationally.
  • About 9% of Wisconsin’s mercury air emissions come from a variety of much smaller sources, including electric lamp and mercury switch breakage, laboratory and dental use, secondary metal smelting, manufacturing and lime production.[3]
  • Industrial facilities release over 4,000 pounds of mercury in Wisconsin per year, with 58% coming from power plants:[8]

WI_Ind_Hg_2011

  • 14 power plants in Wisconsin reported mercury air emissions in 2011:[8]
Reported Mercury Emissions from Power Plants Reporting in Wisconsin, 2011
Facility Parent Company County Zip Reported Mercury Emissions (pounds)
Oak Creek Site Wisconsin Energy Corp Milwaukee 53154 606.5
Columbia Energy Center Alliant Energy Corp Columbia 53954 474.4
Pleasant Prairie Power Plant Wisconsin Energy Corp Kenosha 53158 457
Weston Power Plant Integrys Energy Group Inc Marathon 54474 275
Edgewater Generating Station Alliant Energy Corp Sheboygan 53081 216.9
Dairyland Power Cooperative-Alma Site Dairyland Power Cooperative Buffalo 54610 87.42
Dairyland Power Cooperative – Genoa Site Dairyland Power Cooperative Vernon 54632 77.41
Manitowoc Public Utilities N/A Manitowoc 54220 70.86
Pulliam Power Plant Integrys Energy Group Inc Brown 54303 56.2
Nelson Dewey Generating Station Alliant Energy Corp Grant 53806 45.49
French Island Plant Xcel Energy La Crosse 54603 39.1
Xcel Energy Bay Front Plant Xcel Energy Ashland 54806 20.95
Dte Stoneman Generating Station Dte Energy Co Grant 53806 16.0
Valley Power Plant Wisconsin Energy Corp Milwaukee 53233 0.8

Current Law

State

Wisconsin’s administrative code Chapter NR 446 controls mercury emissions in the state. This rule applies to all air-contaminating mercury emissions sources and establishes both emissions limitations and monitoring requirements.  In general, this rule requires that, starting January 2010, no major utility is permitted to have mercury emissions that exceed 60% of a mercury emissions baseline (determined by the DNR from an average of emissions between 2002 and 2004).[9]

Subchapter III of this code specifically deals with emissions from coal-fired electric utilities. This subchapter took effect in 2004 and was revised in 2008. Under this rule, large power plants (nameplate capacity greater than 150 megawatts, or MW) are required to reduce their mercury emissions by 90% or limit their emissions to 0.008 lbs of mercury per gigawatt-hour by January 2015.  Large power plants may alternatively choose the multi-pollutant option, which gives utilities an extra 6 years to achieve the 90% reduction as long as they also reduce nitrogen oxide (NOx) and sulfur dioxide (SO2) beyond current federal and state regulations.[10]  Small power plants (nameplate capacity between 25 MW and 150 MW) have a choice between achieving mercury emissions limits with the best available control technology (BACT) or complying with the above-mentioned large power plant laws.[11]

Federal

Nationally mercury pollution in the air is regulated by the Clean Air Act. Recently, the EPA finalized specific Mercury and Air Toxics Standards (MATS) within the Clean Air Act that regulate mercury pollution emitted from coal and oil-fired power plants. These standards, announced in December 2011, require power plants to reduce emission of toxic air pollutants through methods such as implementation of available technologies by a set date.[12]

As power plants are the largest source of U.S. mercury emissions to the air, these standards are a valuable step in working to combat toxic mercury pollution.[13] It is estimated that these standards will result in over 2,000 fewer pounds of mercury being emitted in Wisconsin every year. [2] The text of these standards can be found under Section 111 and 112 of the Clean Air Act or in Title 42, Chapter 85, Sections 7411 and 7412 of the U.S. Code.

Cited Resources
  1. U.S. Environmental Protection Agency. “Basic Information – Mercury.” Web. Retrieved 2012 from http://www.epa.gov/hg/about.htm.
  2. Wisconsin Department of Natural Resources. “Mercury Rule Media Kit.” Web. Retrieved 2013 from http://dnr.wi.gov/news/mediakits/mk_mercury.asp
  3. Wisconsin’s Environmental Decade. “Troubled Waters – Mercury in Wisconsin’s Lakes and Fish.” (2005)
  4. U.S. Environmental Protection Agency. “Mercury Emissions: The Global Context.” Web. Retrieved 2012 from http://www.epa.gov/hg/control_emissions/global.htm. (2012)
  5. U.S. Environmental Protection Agency. “What are the biggest sources of mercury air emissions in the U.S.?” Web. Retrieved 2013 from http://publicaccess.supportportal.com/ics/support/KBAnswer.asp?questionID=21198&subscribe=1 (2013)
  6. Wisconsin Department of Natural Resources. “Wisconsin Mercury Sourcebook.” Bureau of Watershed Management (May 1997)
  7. Wisconsin Environment. “Dirty Energy’s Assault on our Health.” (January 2011)
  8. U.S. Environmental Protection Agency. “Toxics Release Inventory (TRI) Program.” Web. Retrieved 2013 from http://www.epa.gov/tri/index.htm (n.d.)
  9. Wis. Adm. Code NR 446
  10. Wisconsin Department of Natural Resources. “Air Toxics and Mercury – Coal Fired Utility Rule.” Web. Retrieved 2012 from http://dnr.wi.gov/topic/AirQuality/Toxics.html (2012)
  11. Wisconsin Department of Natural Resources. “Factsheet on Rule to Control Mercury Emissions From Coal-Fired Power Plants.” Bureau of Air Management (2008)
  12. U.S. Environmental Protection Agency. “Regulatory Actions – Mercury and Air Toxics Standards (MATS) for Power Plants.” Web. Retrieved 2013 from http://www.epa.gov/mats/actions.html
  13. U.S. Environmental Protection Agency. “Basic Information – Mercury and Air Toxics Standards (MATS) for Power Plants.” Web. Retrieved 2013 from http://www.epa.gov/mats/basic.html

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