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The state’s largest coal-burning power plants are putting new, multi-million dollar “scrubbers” to work on their emissions. The state-of-the-art technology captures pollutants - and enables utilities to mark a milestone in complying with the requirements of the Maryland Healthy Air Act.
The first phase of the Healthy Air Act requires power companies to reduce emissions of nitrogen oxide (NOx) by almost 70 percent in 2010, compared to 2002. Both sulfur dioxide and mercury emissions must be reduced by 80 percent this year.
The power plants will have to achieve even greater reductions by 2013. These terms make the Healthy Air Act the toughest power plant emission law on the East Coast. The Act’s regulations represent, in short, the most sweeping air pollution program ever in Maryland.
The Healthy Air Act was developed to assist Maryland with meeting federal air quality standards for ozone, fine particles, and mercury.
NOx is the most significant pollutant contributing to Maryland’s ground-level ozone problem. Sulfur dioxide is the most significant contributor to the fine particle problem, playing a significant role in creating regional haze that decreases visibility.
Health effects associated with ozone include decreased lung function, asthma attacks, and eye irritation. Excess levels of fine particles can cause premature deaths, heart attacks, and respiratory problems.
NOx also contributes significantly to the nutrient pollution in the Chesapeake Bay and other waterways. More than a third of the pollution entering the Bay comes from the air. Emission controls on power plants will reduce the amount of nitrogen entering the Bay by as much as 900,000 pounds a year and will also reduce the amount of mercury entering the water.
Reducing mercury in our environment is important to protect the health of all Marylanders because mercury is a highly toxic metal that bioaccumulates in fish; ten species of fish are currently subject to mercury consumption advisories in our State.
The Healthy Air Act was signed into law in 2006. The Maryland Department of the Environment is responsible for implementing the Act through regulations that became effective in 2007.
More than 95 percent of the air pollution from Maryland’s power plants comes from the largest and oldest coal burning plants. Those facilities have installed controls - at an estimated total cost of more than $2 billion - to meet the requirements of the first phase of the Healthy Air Act.
Scrubbers remove sulfur from coal burning gases by using limestone to "absorb" some of the sulfur dioxide. Nitrogen is removed using a different type of technology that uses ammonia or urea to help remove NOx from a large smokestack. In combination, the sulfur dioxide and NOx technologies remove a great deal of mercury from a smokestack. Mercury removal can be aided through a technology called carbon injection. What is left is largely water vapor, some carbon dioxide, and greatly reduced amounts of other pollutants.
Scrubbers have been installed at Constellation’s Brandon Shores power plant and at Mirant’s Morgantown, Chalk Point, and Dickerson facilities.
Thanks in part to the reduction in sulfur dioxide emissions, fine particle levels in Maryland are now better than federal standards. Future reductions in NOx emissions will be a key building block for Maryland’s plans to meet tougher ozone standards due to be announced this year by the U.S. Environmental Protection Agency.
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