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North Carolina Division of Air Quality - Mercury Regulations, Emissions, and
Deposition Modeling in North Carolina
Presented for
6th Annual Unifour Air Quality Conference Hickory, NC
June 15, 2012
By Steve Schliesser
Division of Air Quality (DAQ)
Environmental Engineer
BRUNSWICK
NEW HANOVER
COLUMBUS
PENDERBLADEN
RO BESON
SCOTLAND
DUPLINANSON
HO KERICHMONDSAMPSONUNION
CLAY JONESPAMLICO
CHEROKEE MACONTRANSYLVANIA
CLEVELANDLENOIRLENOIRMECKLENBU RG
CRAVENGASTON
JACKSON MOOREPOLK STANLY
GRAHAM HARNETTHENDERSONRUTHERFORD
GREENELEELINCOLN
PITT
SWAIN
HAYWOODHYDEJOHNSTON
WAYNE
BEAUFORTBUNCOMBE
CATAWBACHATHAM
MCDOWELLRANDOLPH
ROWAN
BURKEDARE
MARTIN WASHINGTON
WILSON
DAVIDSON TYRRELLWAKE
DAVIE EDGECOMBEMADISON YANCEY
ALEXA NDERCALDWELL
GUILFORD BERTIENASH
AVERY FORSYTHFRANKLIN
ORANGE
WATAUGAWILKES
YADKIN
HALIFAXHERTFORD
SURRY WARRENASHE
CASWELLGATESPERSONROCKINGHAMSTOKES
VANCE
ALLEGHANYNORTHAMPTON
DURHAM
Topics Covered
2002 NC Clean Smokestack Act
2012 EPA Electric Generating Unit (EGU) Rules
Statewide mercury emissions from 2002-2025
Principal mercury emission sources
Mercury deposition modeling results
Why Interest for Mercury in North Carolina back in 2002?
Mercury in fish tissue prompted NC fish advisories
Coal-fired power plants released 3,200 pounds of mercury for 2/3 of NC emissions
Limited data available on speciated mercury emissions
Mercury emission control varied from 0-90+% for U.S. power plants, questions as to why
Little known about relationship among emissions, deposition, and fish tissue level for mercury.
2002 North Carolina Clean Smokestack Act (CSA)
Officially Air Quality/Electric Utilities Act (SB 1078)
Require coal-fired power plant reductions of 73% for sulfur dioxide (SO2) & 77% nitrogen oxides (NOx)
SO2 and NOx controls also reduce mercury emissions
Requires DAQ to evaluate mercury emission control and recommend any development of standards and plans
Utilities Response to Clean Smokestack Act
From 2005-2010 NC utilities spent $2.9 billion installing:
- Selective catalytic reduction (SCR) or Selective non-catalytic reduction (SNCR) units for NOx control
- Flue gas desulfurization (FGD) scrubbers for SO2 control SCR/SNCRs reduce NOx by 80% and condition mercury
emissions to be more collectable FGDs collect 99% of SO2 emissions, and SCR/SNCR-ESP-FGD combination collect 90+%
mercury
EPA Electrical Generating Units (EGU) Mercury and Air Toxics Standards Rule
Maximum Achievable Control Technology Rule
(40 CFR part 63 subpart UUUUU)
aka EGU MATS (Mercury and Air Toxics Standards)
Compliance by April 2015 with 1-year extension option
Numerical emission limits Mercury Particulate matter / toxic metals Acid gases (SO2 or Hydrogen chloride)
NC Coal-Fired Utility Boilers EGU Pre-MATS 2010 Status
For 13 gigawatts (GW) of NC EGU capacity:
7 facilities with 10 GW capacity and 19 largest boilers
- Most well-positioned to meet EGU MATS standards
- All will continue to operate
7 facilities with 3 GW capacity and 26 smallest boilers
- None can meet any EGU MATS standards
- All retired by 2015
Pollutant NOx
PM/ Metals
HCl/ SO2
Mercury PM HCl SO2 Hg
Emission Controls lb/MMBtu lb/TBtu
EGU MATS limits 0.03 0.002 0.2 1.2 Average of 19 largest boilers - CSA controls
SCR/ SNCR
ESP FGD All 3 0.03 0.001 0.19 0.8
Average of 26 smallest units – few/no CSA controls
No SCR/ SNCR
ESPNo
FGDESP 0.15 0.24 1.5 5.0
Emission Ratio smallest/largest 5 150 8 7
NC Coal-Fired EGU Pre-MATS 2010 Emission Performance
North Carolina Mercury Emissions from 2002-2025
2002 2005 2010 2015 2018 2023 20250
500
1,000
1,500
2,000
2,500
3,000
3,500
Reported to DAQ Projections by Utility Companies
Mercury Emissions,
lb/yr
EGU emission reductions from 2002:>70% by 2010
> 80% by 2025
EPA Airborne Mercury Deposition Modeling
EPA performed deposition modeling for EGU MATS
Used Community Multi-scale Air Quality (CMAQ) Model
Modeled with 3 scenarios:
1. Base year with 2005 emissions (Pre-rule)
2. Projected 2016 emission data (Post-rule)
3. Projected 2016 emissions without U.S. EGU emissions
EPA Modeling Observations for U.S. Nationwide Deposition
Patterns of total and US EGU-related mercury deposition differ considerably: Elevated deposition areas distributed, several in east close to EGUs.
US deposition dominated by sources other than EGUs;
-EGUs contribute 5% deposition for 2005, 2% for 2016.
In 2005, US EGUs contributed 5% deposition in US,
but up to 30% for certain watersheds.
DAQ Deposition Modeling Results for NC Scenarios
2005 with EGUs 2016 with EGUs 2016 without EGUs
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
Mercury Deposited in NC Mercury Emitted from NC sources
Mercury, lb/yr
Summary of Mercury Deposition Modeling
EPA modeling suggests deposition in NC should decrease by 10% between 2005 and 2016.
DAQ modeling indicates 16% of NC deposition comes from NC sources in 2005, down to 3% by 2016.
70% of mercury deposition in NC originates from outside the central and eastern United States.
Questions?
Steve SchliesserNC DAQ Environmental Engineer
919-707-8701 [email protected] http://www.ncair.org
DAQ Clean Smokestack Act website: http://daq.state.nc.us/news/leg/
EPA EGU MATS website: http://www.epa.gov/airquality/powerplanttoxics/index.html