Mercury and CoalFired Power Plants: Science, Technology, and Emerging States and Federal Regulations

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Mercury and Coal-Fired Power Plants Science,
Technology, and Emerging States and Federal (?)
Regulations

• Praveen Amar
• NESCAUM
• MIT Endicott House Symposium on Air Toxics
• August 3-5, 2004

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Mercury Emissions and Human Exposure
Ocean
Atmospheric deposition

• Fishing
• commercial
• recreational
• subsistence

• Impacts
• Best documented impacts on the developing fetus
  impaired motor and cognitive skills
• Also cardiovascular, immune, and reproductive
  system impacts

Humans and wildlife affected primarily by eating
contaminated fish
Wet and Dry Deposition
Power Plant Emissions
Mercury transforms into methylmercury in soils
and water, then can bioaccumulate in fish
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Overview of This Session

• Context Emerging states and federal proposals
  on controlling mercury emissions from coal-fired
  power plants
• Current research on sources of and trends in Hg
• Gerald Keeler ( Great Lakes Region, Northeast)
• Tom Atkeson ( Florida mercury science program,
  recent trends)
• Status of control technologies and costs
• Ravi Srivastava ( EPAs perspective)
• Paul Chu (EPRI program)

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Global Sources of Mercury to the Atmosphere (in
metric tons per year)
Most scientists agree on the total input of
mercury to the atmosphere and the relative amount
of this mercury that has come from anthropogenic
sources (about two thirds of the total).
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Total U.S. Mercury Emissions by Source Category
Source U.S. EPA

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Simplified Mercury Cycle
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Atmosphere and Deposition
Atmospheric Transport

• Mercury is emitted from sources in one of three
  forms elemental, ionic (also called reactive or
  divalent), and particulate
• Elemental mercury is slowly converted to ionic
  mercury in the atmosphere
• Elemental mercury can travel quite far before it
  deposits, so it tends to enter the global pool
  and deposit far from its initial source
• Ionic mercury deposits quickly, especially in
  rain, and so tends to deposit relatively near to
  its initial source
• Estimates vary, but current U.S. emissions are
  thought to account for over half of the
  atmospheric deposition in the U.S. (on average)
• Near sources the percentage is even higher

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Atmospheric Transport of Mercury
At the point where modeled deposition is the
highest, in-state sources are responsible for
more than 50 of the deposition in many states.
In most places the contribution of U.S. sources
to mercury deposition in the U.S is somewhere in
between.
States with the highest levels of mercury
deposition in-state sources in 9 of these 10
states contribute more than 50 of that deposition
amount of deposition
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Total Wet Mercury Deposition (2002)
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Mercury Policy Context in the Northeast

• New England Governors/Eastern Canadian Premiers
  Regional Mercury Action Plan (1998)
• 50 reduction by 2003
• 75 reduction by 2010
• Virtual elimination of anthropogenic discharges
  of mercury is long-term goal

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Proposed U.S. Regulatory Alternatives

• Regulatory options outlined in the January 30,
  2004, EPA proposal (600,000 comments in the
  Docket !)
• Section 112 of CAA
• Performance-based MACT requirements (about 29
  reduction by 2007-2008)
• Cap-and-trade approach under guidelines of
  section 112(n)(1)(A) about 29 reduction by
  2007-2008
• Section 111 of CAA
• Market-based, cap-and-trade approach (70 red.
  by 2018 29 reduction likely by 2010)
• Final rule to be promulgated by March 15, 2005

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States and Federal Mercury Regulations/Legislation

• The proposed federal regulations uncertain
  future
• Pending federal legislation passage this year
  questionable
• States A number of state regulations already in
  place in view of uncertainty at federal level

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Where are the NESCAUM States ?

• Control technologies are now commercially
  available new technologies are rapidly emerging
  90 and higher control is feasible great
  experience with MWCs (up to 98 reduction)
• Cost effectiveness of Hg control is quite
  comparable to, and more attractive than the cost
  effectiveness of SO2 and NOx controls from power
  plants (HgSO2NOx1-3 mills/kwhr 3-5
  mills/kwhr2-3 mills/kwhr)
• Many states in the NE are moving at a faster and
  a more certain pace than the federal regulation
  (85 to 95 red. by 2007-2012), based on the
  assumption that environmental regulation drives
  technology innovation and implementation
• Northeast States strongly opposed to mercury
  emissions trading