Controlling Mercury Emissions Controlling Mercury Emissions from U.S. Coal Power Plantsfrom U.S. Coal Power Plants

Michael WeberMichael Weber

CBE 562CBE 562

April 11, 2005April 11, 2005

Part of Clear Skies InitiativePart of Clear Skies Initiative

Cut sulfur dioxide (SO2) emissions by 73 percentCut sulfur dioxide (SO2) emissions by 73 percent, from year 2000 , from year 2000 emissions of 11 million tons to a cap of 4.5 million tons in 2010 and to a cap of emissions of 11 million tons to a cap of 4.5 million tons in 2010 and to a cap of 3 million tons in 2018. 3 million tons in 2018.

Cut emissions of nitrogen oxides (NOx) by 67 percentCut emissions of nitrogen oxides (NOx) by 67 percent, from year 2000 , from year 2000 emissions of 5 million tons to a cap of 2.1 million tons in 2008 and to a cap of emissions of 5 million tons to a cap of 2.1 million tons in 2008 and to a cap of 1.7 million tons in 2018. 1.7 million tons in 2018.

Cut mercury emissions by 69 percentCut mercury emissions by 69 percent - the first-ever national cap on - the first-ever national cap on mercury emissions. Emissions would be cut from 1999 emissions of 48 tons to mercury emissions. Emissions would be cut from 1999 emissions of 48 tons to a cap of 26 tons in 2010 and to a cap of 15 tons in 2018.a cap of 26 tons in 2010 and to a cap of 15 tons in 2018.

Clear Skies has not yet gotten through a Republican dominated Clear Skies has not yet gotten through a Republican dominated subcommittee, which voted against it two weeks ago. However, subcommittee, which voted against it two weeks ago. However, the EPA has instituted Mercury regulations, which are very similar the EPA has instituted Mercury regulations, which are very similar to those proposed under Clear Skies.to those proposed under Clear Skies.

The clear skies act is designed to reduce emissions of the most troublesome air pollutants:

Note: The clear skies initiative does not address carbon dioxide emissions.

“Clear Skies” vs. Existing Clean Air Act Programs

Source: Comparison table being circulated on web, particularly by environmentalists. EPA meetings and reports are cited.

Sources Contributing to Hg in the EnvironmentSources Contributing to Hg in the Environment

Fossil fuel combustion by utility boilers, Fossil fuel combustion by utility boilers, particularly coal combustionparticularly coal combustion

Municipal waste combustorsMunicipal waste combustors Medical incineratorsMedical incinerators Consumer productsConsumer products Mercury used in certain chemical processesMercury used in certain chemical processes

How Mercury Enters the Food-ChainHow Mercury Enters the Food-Chain

Source: Sierra Club

Inorganic Mercury to Methylated MercuryInorganic Mercury to Methylated Mercury

Source: Adapted from Winfrey, M.R. and J.W.M. Rudd. 1990. Review -- Environmental Factors Affecting the formation of Methylmercury in Low pH Lakes. Environ. Toxicol. Chem. 9:853-869.

Mercury in HumansMercury in Humans ExposureExposure

– Primary source of exposure is through contaminated fishPrimary source of exposure is through contaminated fish– Ingestion of methyl-mercury contaminated drinking waterIngestion of methyl-mercury contaminated drinking water– Dermal up take through water and soilDermal up take through water and soil

Mercury is a known human toxicant, which primarily affects the nervous Mercury is a known human toxicant, which primarily affects the nervous systemsystem– at low doses mercury can cause a decrease in motor skills and at low doses mercury can cause a decrease in motor skills and

sensory abilitysensory ability– at higher doses mercury exposure can lead to tremors, inability to at higher doses mercury exposure can lead to tremors, inability to

walk, convulutions and deathwalk, convulutions and death– links are suspected between mercury and neurological diseases links are suspected between mercury and neurological diseases

such as autism and alzheimerssuch as autism and alzheimers

Greatest Concern: Exposure to Developing Greatest Concern: Exposure to Developing Fetuses and Young ChildrenFetuses and Young Children

U.S. RfD calculated for methylmercury exposure based upon U.S. RfD calculated for methylmercury exposure based upon examining 81 Iraqi children whose mothers who had eaten bread examining 81 Iraqi children whose mothers who had eaten bread contaminated with mercury during pregnancycontaminated with mercury during pregnancy

Children were examined approximately 30 months after birth and Children were examined approximately 30 months after birth and showed the following adverse effects:showed the following adverse effects:– Late walkingLate walking

– Late talkingLate talking

– SeizureesSeizurees

– Delayed mental developmentDelayed mental development

– Low scores on clinical tests of nervous system functionLow scores on clinical tests of nervous system function

U.S. EPA calculated a mercury RfD for pregnant mothers of 0.1 micrograms per kilogram body weight per day.

Source: JAMA -- Abstract Blood Mercury Levels in US Children and Women of Childbearing Age, 1999-2000, April 2, 2003, Schober et al_ 289 (13) 1667

Environmental ImpactEnvironmental Impact

Fish-eating birds and mammals are most Fish-eating birds and mammals are most susceptible to mercury poisoningsusceptible to mercury poisoning– Wisconsin furbearers such as otters and minkWisconsin furbearers such as otters and mink– Avian predators such as osprey and eaglesAvian predators such as osprey and eagles

Massive poisonings of birds and other wildlife Massive poisonings of birds and other wildlife were identified from birds and other wildlife that were identified from birds and other wildlife that ate grains that were treated with methylmercuryate grains that were treated with methylmercury

Concentrations of mercury in the tissues of wildlife species have been reported at levels associated with adverse health effects in laboratory studies in the same species.

TechnologyTechnology

Methods of mercury removal include: Carbon filter beds Wet scrubbing Depleted brine scrubbing Treated activated carbon adsorption Selenium filters Coal Cleaning Activated carbon injection

Activated Carbon InjectionActivated Carbon Injection Activated carbon injection has received the most Activated carbon injection has received the most

attention as a means of removing Hgattention as a means of removing Hg

Estimated potential of removing approximately Estimated potential of removing approximately 90% of mercury 90% of mercury

How it works:How it works:– Powered activated carbon sorbent is injected into the Powered activated carbon sorbent is injected into the

flue gasflue gas– Activated carbon binds with HgActivated carbon binds with Hg– Mercury containing activated carbon capturedMercury containing activated carbon captured

According to a June 2003 article in the Chicago Sun Times, an Illinois Institute Of Technology ChE professor plated the carbon with gold thus increasing its Hgrecovery to 100%.

Cost Effectiveness of Control Technologies for Utility Boilers

Source: December 1997 Mercury Report to Congress by EPA

Potential Mercury Emission Reductions and Costs for Selected Source Categories

Source: December 1997 Mercury Report to Congress by EPA

Another Representation of Cost for 90% Reduction from 1999 Another Representation of Cost for 90% Reduction from 1999 levels of Hg Emissions from Coal Burning Power Plantlevels of Hg Emissions from Coal Burning Power Plant

Source: Economic Analysis of a Multi-Emissions Strategy. Prepared October 31, 2001 by the EPA for senators Jeffords and Lieberman.

SolutionSolutionEPA has investigated two alternatives for controlling emissions of mercury fromUtilities. The alternatives include: 1. proposed rule requiring utilities to install controls known as

“maximum achievable control technologies” (MACT) under section 112 of the Clean Air Act. If implemented, this proposal would reduce nationwide emissions of mercury by 14 tons (29 percent) by the end of 2007; and

2. proposed rule establishing “standards of performance” limiting mercury emissions from new and existing utilities. This proposal, under section 111 of the Clean Air Act, would create a market based “cap-and trade” program that, if implemented, would reduce nationwide utility emissions of mercury in two distinct phases. In the first phase, due by 2010, emissions will be reduced by taking advantage “co-benefit” controls that is mercury reductions achieved by reducing SO2, and NOx.

– EPA is proposing to revise its December 2000 finding that it is “appropriate and necessary” to regulate utility hazardous air emissions using the MACT standards provisions (section 112) of the Clean Air Act. This action would give EPA the flexibility to consider a more efficient and more cost effective way to control mercury emissions.

Revised Rules and Regulations Regulating Revised Rules and Regulations Regulating Mercury Emissions Issued Mar. ’05 by EPAMercury Emissions Issued Mar. ’05 by EPA

Utilities will be required to reduce mercury emissions to 38 tons a Utilities will be required to reduce mercury emissions to 38 tons a year as early as 2010 from 48 tons now and to 15 tons as early as year as early as 2010 from 48 tons now and to 15 tons as early as 2017.2017.

In the first phase, due by 2010, emissions will be reduced by taking advantage “co-benefit” controls– that is mercury reductions achieved by reducing SO2, and NOx.

Environmentalists had agrued current regulations would have Environmentalists had agrued current regulations would have reduced emissions to as little as 5 tons/yr. within 3-5 yrs.reduced emissions to as little as 5 tons/yr. within 3-5 yrs.

According to EPA, mercury emissions in Wisconsin will be According to EPA, mercury emissions in Wisconsin will be Reduced 8% from 1999 levels by 2020 under Clear Skies (likely Reduced 8% from 1999 levels by 2020 under Clear Skies (likely the same as new EPA rule).the same as new EPA rule).

Note: This new regulation is separate from Clear Skies; although, environmental groups contend it is weaker than Clear Skies.

Cap-and-Trade Basics The proposed standards of performance establish a cap-and-trade system for mercury

based on EPA’s proven Acid Rain Program. The Acid Rain Program has produced remarkable and demonstrable results, reducing SO2 emissions faster and at far lower costs than anticipated, and resulting in wide-ranging environmental improvements.

Under the cap-and-trade approach proposed in this rulemaking, EPA would allocate to each state specified amounts of emission “allowances” for mercury. The states would allocate those allowances to utilities, which would trade them. A utility must hold sufficient allowances to cover its emissions each year, so the limited number of allowances ensures that the required reductions are achieved.

The mandatory emissions caps in the proposed standards of performance, coupled with significant automatic penalties for noncompliance, would ensure that human health and environmental goals would be achieved and sustained. At the same time, stringent emissions monitoring and reporting requirements make flexibility possible. The flexibility of allowance trading creates financial incentives for utilities to look for new and low-cost ways to reduce emissions and improve the effectiveness of pollution control equipment.

Text from EPA “Mercury” Factsheet released January 2005.

Maximum Achievable Control or Maximum Achievable Control or Cap-and-Trade SystemCap-and-Trade System

Maximum Achievable ControlMaximum Achievable Control Reduce Hg emmissions from all power Reduce Hg emmissions from all power

plantsplants

Greater reduction of Hg emmissionsGreater reduction of Hg emmissions

Cap-and-Trade SystemCap-and-Trade System Non-uniform distribution of emissionsNon-uniform distribution of emissions

Smaller costSmaller cost

Theoretically minimizes cost for a Theoretically minimizes cost for a specified quantity of emissions reductionspecified quantity of emissions reduction

Technology implemented over a longer Technology implemented over a longer period of time, so more time for period of time, so more time for development of technologydevelopment of technology

Critical Questions Remaining to be Answered•The EPA has said that it does not know the extent to which adverse health effects occur in the United States because of Mercury•Given the current scientific understanding of the environmental fate and transport of Hg, it is not possible to quantify how much of the methylmercury in locally-caught fish consumed by the U.S. population is contributed by U.S. emissions relative to other sources of Hg ( natural and other countries).

Questions???Questions???