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Increases in NOx Emissions in Coal-Fired, SCR-Equipped Electric Generating Units
T. F. McNevin, Ph.D.Division of Air Quality
New Jersey Department of Environmental Protection
NJ Clean Air CouncilPrinceton South Corporate Centre
Ewing, NJJanuary 14, 2015
2
Increases in NOx Emissions in Coal-Fired, SCR-Equipped Electric Generating Units
• Clean Air Act Amendments (1990)– NOx RACT
–OTC NOx Budget Program (1999)• Northeast, Mid-Atlantic States
– “NOx SIP Call” NOx Budget Program (2003-04)• 20 Eastern States
– CAIR (2009)– CSAPR (2012…..)
3
Increases in NOx Emissions in Coal-Fired, SCR-Equipped Electric Generating Units
• Clean Air Act Amendments (1990)– NOx RACT
–OTC NOx Budget Program (1999)• Northeast, Mid-Atlantic States
– “NOx SIP Call” NOx Budget Program (2003-04)• 20 Eastern States
– CAIR (2009)– CSAPR (2012…..)
4
Increases in NOx Emissions in Coal-Fired, SCR-Equipped Electric Generating Units
• Clean Air Act Amendments (1990)– NOx RACT
–OTC NOx Budget Program (1999)• Northeast, Mid-Atlantic States
– “NOx SIP Call” NOx Budget Program (2003-04)• 20 Eastern States
– CAIR (2009)– CSAPR (2015…..)
6
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
NO
x(t
ons)
NJ Ozone Season NOx Emissions
7
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
NO
x(t
ons)
PA Ozone Season NOx Emissions
12
Selective Catalytic Reduction (SCR)
NOx + NH3 catalyst N2 + H2O
TiO2, V2O5, WO3,
Pt, Pd, zeolites
350° - ~1,100 °F
> 90% reduction
19
2014 Ozone Season Excess NOx
in Top 25 Emitters
• OTC Domain 37,750 tons
• CAIR States 36,626 tons
• CSAPR States 32,403 tons
20
What has been Happening?
• Hundreds of coal boilers have installed SCR
• Emission rates fell dramatically 2003-09
21
Ozone Season NOx Emission Rates of SCR-Equipped Coal-Fired EGUs in Eastern US with Number of Units.
0.289
0.256
0.289
0.222
0.247
0.199
0.096
0.081 0.082 0.0860.095
0.086
0.1010.111
0.132 0.130
0
50
100
150
200
250
0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Uni
ts
lb N
Ox
/ m
mBT
U
Rate Number of Units
22
What has been Happening?
• Hundred of coal boilers have installed SCR
• Emission rates fell dramatically 2003-09
• Emission Rates began increasing after 2009
23
Ozone Season NOx Emission Rates of SCR-Equipped Coal-Fired EGUs in Eastern US with Number of Units.
0.289
0.256
0.289
0.222
0.247
0.199
0.096
0.081 0.082 0.0860.095
0.086
0.1010.111
0.132 0.130
0
50
100
150
200
250
0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Uni
ts
lb N
Ox
/ m
mBT
U
Rate Number of Units
24
2013 Ozone Season
• Top 200 Boilers = 66% of NOx
– 198 Coal-fired EGUs– 79 SCR Equipped• Best Observed Rate (BOR), lb/mmBTU
– ≈68%, 2013 Emission Rate > BOR– Ratio (79 Units): 1.0 – 9.2, Mean = 3.3
25
Ozone Season NOx Emission Rates of Coal-Fired Units in OTC Modeling Domain with Reduced SCR Operations within the 2013 Top 200 Emitters.
0.245
0.103
0.085 0.085
0.095
0.112
0.097
0.126
0.175
0.230 0.232
0.000
0.050
0.100
0.150
0.200
0.250
0.300
2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
lb N
Ox
/ m
mBT
U
26
Ozone Season NOx Emission Rates of Coal-Fired Units in OTC Modeling Domain with Reduced SCR Operations within the 2013 Top 200 Emitters.
0.245
0.1030.085
0.085
0.095
0.112
0.097
0.126
0.175
0.2300.232
0.000
0.050
0.100
0.150
0.200
0.250
0.300
2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
lb N
Ox
/ m
mBT
U
27
What Happened?
• Collapse of CAIR allowance costs– $4,600/ton January 2009, $51/ton October 2012• Oversupply of allowances• Market uncertainty
– Less than forecast electric demand
28
Total US Annual Electrical Generation.
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
5,000
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
TWh
1.3% Annualized Growth from 2000
-0.7% Annualized Growth from 2007
What Happened?
• Collapse of allowance costs– $4,600/ton January 2009, $51/ton October 2012• Oversupply of allowances• Market uncertainty
• Less than forecast electric demand– 2008-13 Top 200 NOx emitters, GLOAD -1.7%
• Increased gas-fired generation
29
What Happened?
• Oversupply of allowances• $4,600/ton January 2009, $51/ton October 2012
• Oversupply of allowances• Market uncertainty
• Less than forecast electric demand– 2008-13 Top 200 NOx emitters, GLOAD -1.7%
• Increased gas-fired generation– April 2012, Coal = Gas = 32%
31
35
0.00
0.05
0.10
0.15
0.20
0.25
$-
$1.00
$2.00
$3.00
$4.00
$5.00
$6.00
$7.00
$8.00
lb /
mm
BTU
Total Allowance Costs ($/MWh) Natural Gas ($/mcf) Emission Rates (lb/mmBTU)
Total Monthly Average Ozone Season Allowance Costs at 3.0 lb NOx / MWh, Monthly Average Natural Gas Electrical Generation Costs, "53 SCR Boiler" Average Ozone Season Emission Rates.
37
0.00
0.05
0.10
0.15
0.20
0.25
$-
$1.00
$2.00
$3.00
$4.00
$5.00
$6.00
$7.00
$8.00
lb /
mm
BTU
Total Allowance Costs ($/MWh) Natural Gas ($/mcf) Emission Rates (lb/mmBTU)
Total Monthly Average Ozone Season Allowance Costs at 3.0 lb NOx / MWh, Monthly Average Natural Gas Electrical Generation Costs, "53 SCR Boiler" Average Ozone Season Emission Rates.
Approximate SCR Ammonia Cost / MWh
38
Low
Alabama Arkansas Georgia Maryland
0.077 0.068 0.061 0.074
High
Missouri New Hampshire
New York Pennsylvania
0.376 0.274 0.323 0.247
Arizona Colorado Kansas Montana Nevada Texas Wyoming
0.076 0.067 0.087 0.079 0.064 0.056 0.057
CAIR-region States with Representative Low and High Average NOx Emission Rates, (lb/mmBTU), of SCR-Equipped Coal-Fired EGUs in the 2013 Ozone Season.
Average 2013 Ozone Season NOx Emission Rates, (lb/mmBTU), of SCR-Equipped Coal-Fired EGUs in Western States that are not in the CAIR Cap and Trade Program.
Reduced, “Sub-Optimal” SCR Operation
NOx Emission Rates, lb/mmBTU
Plant Location Best Year 2009 2010 2011 2012 2013 PA 0.044 (2003) 0.113 0.212 0.316 0.414 0.424
MO 0.090 (2009) 0.090 0.108 0.230 0.627 0.609
KY 0.123 (2006) 0.127 0.320 0.307 0.349 0.812
WV 0.071 (2004) 0.080 0.260 0.206 0.304 0.300
NC 0.070 (2004) 0.132 0.104 0.116 0.243 0.247
IL 0.071 (2004) 0.127 0.124 0.137 0.214 0.245
39
41
1 2
57
12 11
14
4 5
10
14
20
2428
16 16
28
34
44
42
49
0
10
20
30
40
50
60
2008 2009 2010 2011 2012 2013 2014
EGU
s
Ozone Season
Numbers of SCR-Equipped EGUs in Top 25, 50, and 100 NOx Emitters in CAIR States
Top 25 Top 50 Top 100
420
1,000
2,000
3,000
4,000
5,000
6,000
7,000
2008 2009 2010 2011 2012 2013
NO
x(t
ons)
NJ EGU Ozone Season NOx Emissions
430
10,000
20,000
30,000
40,000
50,000
60,000
2008 2009 2010 2011 2012 2013
NO
x(t
ons)
OH EGU Ozone Season NOx Emissions
440
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
2008 2009 2010 2011 2012 2013
NO
x(t
ons)
MD EGU Ozone Season NOx Emissions
450
10,000
20,000
30,000
40,000
50,000
60,000
70,000
2008 2009 2010 2011 2012 2013
NO
x(t
ons)
PA EGU Ozone Season NOx Emissions
460
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
2008 2009 2010 2011 2012 2013
NO
x(t
ons)
MO EGU Ozone Season NOx Emissions
47
0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
0.400
0.450
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
lbs/
mm
BTU
Year
Ozone Season NOx Emission Rates of PA Coal-Fired EGUs with SCR
OTC Program "NOx SIP Call" Program CAIR Program
51
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014Ozone Season
Fraction of PA SCR-Equipped, Coal-Fired NOx vs. Total NOx Emissions
53
Total Excess NOx Emissions (tons) from Coal-Fired SCR-Equipped EGUs in 2013
Top 200 Emitters in Eastern US
Total = 255,900 tons
2010 2011 2012 2013 201427,600 41,100 59,000 61,500 66,700