MERCURY INFORMATION PAGE

MERCURY PROBLEMS

Mercury is exposed to the atmosphere through emissions and settles in soil and water.  The mercury is converted by bacteria to methylmercury, which is toxic to both animals and humans.  The most common way that humans become exposed to mercury is through ingestion of fish that are contaminated by the polluted water they live in.  Fish absorb methylmercury from water as it passes over their gills.  Higher levels of mercury contamination are found in larger fish because they feed on smaller contaminated fish in a process called bioaccumulation.  Thus larger fish, like tuna, often have unsafe mercury levels. 

Extended exposure to mercury can damage the brain, kidneys and central nervous system.  The biggest and most common problems come in the central nervous system.  The mercury is transported to the brain where it interferes with cell differentiation and division by binding to the DNA/RNA, interferes with nerve cell migration, and prevents development of normal brain structure.  Direct results can be mental retardation, autoimmune deficiencies and other neurological problems.  The Seychelles study (Myers and Davidson, 2003) support these findings.

Most danger from mercury poisoning is found in young women of childbearing age (15-49) and children.  Mercury contaminated blood can pass through the placenta to the unborn fetus.  This poisoning is especially harmful for the fetus and small children because the mercury levels constitute a larger proportion of their blood.  The CDC states that as many as 600,000 children born each year may be born with unhealthy levels of mercury in their blood.  This is due to the estimated 8% of women of child-bearing age with blood levels of mercury that exceed the “safe” level of 3.5 parts per billion share of total blood volume.  The mother does not need to show any signs of mercury poisoning to be at risk or have their baby at risk.  Exposure doesn’t have to come during pregnancy, for prior exposure to mercury can persist in tissue and is slowly excreted from the body.  The danger of transferring mercury poisoning from mother to child is supported by the study “Measuring maternal seafood diet, methylmercury neonatal neurological function” (Steuerwald and Weihe, 2000). 

The EPA claims that no entire wildlife fish-eating population is at risk except the Florida Panther, but local subsets of wildlife are at risk. 

MERCURY AND COAL BURNING POWER PLANTS

Data suggests that human activity has increased mercury levels in the environment 3 fold, even higher in industrial areas.  Coal burning plants present the highest level of mercury contamination, around 33%, yet were excluded from emissions regulations by the original Clean Air Act because of the strong coal lobby.  The EPA issued guidelines for hospital/medical/infectious waste incinerators and municipal waste combustors, other high mercury emission sources, in 1997 and have been able to reduce mercury emissions by over 90%.   Major reductions were also aided by reducing the amount of medical waste being incinerated, once the new standards made it more expensive.  Mercury exposure is still widespread in waters, however.  More than 12 million acres of lakes and 400,000 miles of rivers are under advisory, which warns people to limit the fish consumption from those sources.  To this point, 45 states have been forced to issue health advisories for eating fish from local contaminated waters. 

LEGISLATION OF MERCURY EMISSIONS

The Clean Air Act (CAA) was implemented on Dec.31, 1970, but has been amended many times, the last time in 1990.  This act mandates that the EPA control airborne pollution hazards to public health or natural resources.  The enforcement of these mandates are carried out by the states in state implementation plans.  The CAA calls for a Maximum Achievable Control Technology (MACT) in section 112.  The MACT requires averaging the rate of emission control from the top 12% of similar plants using the latest and most effective technology.  If the MACT requirements were enforced by the EPA on coal burning power plants, it would require a 91% emission reduction and each plant would be required to adhere to the MACT standards by 2008.   In response to the neglecting of power plant regulation under the CAA, environmental groups sued the EPA and won.  The lawsuit stipulated that the EPA perform 4 steps on mercury regulation: 1. Collect information on mercury emissions from coal burning plants and submit their findings 2. If there was a positive correlation, they must issue regulatory findings by December 15, 2003 3. They must then submit final regulations by December 15, 2004 4. Implementation would have to begin within 3 years as stated in CAA.  In 2001, the EPA made a report to the coal industry in which it made them aware that the MACT standards would necessitate a 90% reduction in mercury emissions using existing reduction technologies.  This would reduce the emission of mercury from 49 tons annually to 5 tons by 2008, and could be achieved by entire industry by 2010. 

On Earth Day 2002, the Bush Administration unveiled its Clear Skies Initiative (CSI), which was meant to revise the CAA regulations.  Some provisions of the CSI would necessitate passing by Congress, but others only need the EPA to change their interpretation of existing laws.  The CSI was designed to reduce emissions of SOx, NOx and mercury using “market-based” strategies and voluntary programs.  The new plan would call for 29% reductions in mercury emissions by 2010 and 69% reductions by 2018.  This two step plan would allow 21 more tons of mercury emissions annually in the first phase and 10 tons more mercury emissions annually by the 15th year and beyond, than the existing MACT requirement under section 112 of the CAA.  This approach treats the mercury emissions as non-hazardous air pollution and determines that they do not need to be regulated under section 112 of the CAA.

The “market based” strategy includes a “cap and trade” policy that gives a certain amount of credits, which represent allowed amounts of mercury emissions, to each power plant.  The plants could then trade these credits to other coal plants that do not wish to decrease their emissions.  Thus, there would be a cap of the amount of credits given, but the trading would allow certain heavy polluters to continue emitting mercury.  This would cause mercury “hot spots” where the water is heavily polluted with mercury due to the trading of emissions credits. 

These new revisions to the CAA were outlined in the EPA’s report, The Proposed Rule.  This report abandoned the MACT requirements in favor of more “flexible” requirements to meet industry needs, citing the MACT requirements as too strict for the evolving power industry.  Furthermore, the new report claimed that the MACT standards would only call for a reduction of 30% of mercury emissions by 2008, a statement that goes against their previous presentation to coal representatives and most other reports that found that the MACT requirement would call for 91% emission reduction.  The Proposed Rule report also falsely claimed that only existing technologies can be viably used to reduce mercury emissions, whereas there is actual specific and effective technology for reducing mercury implemented today by the Alabama Power 272-MW Plant Gaston by the initiation of the Department of Engineering. 

TECHNOLOGICAL SOLUTIONS

There are numerous technological solutions being implemented and improved to reduce the mercury emissions from coal burning power plants significantly and economically.  The main technology being used and discussed is Activated Carbon Injection (ACI).  ACI can effectively reduce mercury emissions 90% by a process that injects dry powder carbon into the flue gas duct before it reaches the filters.  The mercury is then absorbed with the newly introduced carbon to form a compound that is easier to catch in the filters.  The ACI can be used in conjunction with electrostatic precipitators (ESP), which charges the gas particles to be removed by oppositely charged collection plates, or baghouses, a type of fabric filter.  The baghouses have been shown to perform better in reducing mercury emissions and necessitate 5 times less carbon powder when in conjunction with an ACI device.  Therefore, retrofitting a baghouse instead of the ESP will pay back in 3-4 years after the switch. 

There is another new technology on the market, in use in the Alabama Gaston Plant, called the Compact Hybrid Particulate Collector (COHPAC).  This device, in conjunction with the ACI, allows the flyash to be mainly caught before the carbon injection.  This allows the power plant companies to resell the flyash they collect.  The flyash is resold in order to make concrete.  If there is carbon injected into the flyash then it becomes unable to resell, so this new technology will make it more cost effective to change to cleaner emissions technologies.  The determination by the EPA in their Proposed Rule Report that sorbent injection systems are “not currently available on a commercial basis” is not true, and furthermore, these new technologies are no more expensive to implement than those currently used to diminish NOx from emissions. 

Another technology on the market is enhanced wet scrubbing.  These wet scrubbers push the air past a sprayed liquid.  The liquid then absorbs particles and some of the gases out of the air.  These scrubbers are not as effective as their ACI counterparts at reducing mercury emissions. 


SOURCES:

“Mercury Emissions from Coal-Fired Plants: The Case for Regulation” North East States for Coordinated Air Use Management (NESCAUM): August, 2003

www.pollutionengineering.com

“Briefing: Atmospheric Mercury and Technology Choices” Robert Day, Expansion Capital: 2004

“Proposed Nation Emission Standards for Hazardous Air Pollutants; and, in the Alternative, Proposed Standards of Performance for New and Existing Stationary Sources: Electric Utility Steam Generating Units” Waterkeeper Alliance:  June 15, 2004

“Proposed Rule” Environmental Protection Agency: 2004

www.environmentaldefense.org

www.psr.org


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