What Does the Science Say about Future NOx Control Policy to
Reduce Ozone?
Air Quality Applied Sciences Team 7th Semiannual Meeting
Harvard University
Cambridge, MA June 18, 2014
Paul Miller Deputy Director
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About NESCAUM • Northeast States for
Coordinated Air Use Management
• Association of 8 Northeast state air agencies
• Formed in 1967
• Technical and policy support for air quality & climate initiatives
Ozone Remains Key Challenge for State Air Quality Planners
• States have spent decades on ozone planning efforts
• National ozone health standard has become more stringent to reflect evolving science
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Track Record
• Learning curve sometimes flat, sometimes steep
• Initial efforts largely urban-focused and relied on VOC controls
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A Rethinking
• 1992 – “Rethinking the Ozone Problem…” (Natl. Research Council report)
• Findings: – Regulatory ozone programs over previous 20
years largely failed
– VOC emissions significantly underestimated, resulting in misdirected control strategies
– NOx controls necessary in many parts of U.S.
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Regional NOx Strategy in the East
• EPA promulgated new strategy in 1998 • 1st regional NOx control program in U.S. for
ozone • Covered 20 eastern states • Power plants required to reduce NOx
emissions by May 1, 2003
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Regulatory trends for 8-hr O3 std.
E.g., New York ozone monitors ‒ annual 4th max., 8-hr, 3-yr avgs 1997-1999 1998-2000 1999-2001 2000-2002 2001-2003 2002-2004 2003-2005 2004-2006 2005-2007 2006-2008 2007-2009 2008-2010 2009-2011 2010-2012 2011-2013
0.080 0.077 0.080 0.083 0.086 0.080 0.076 0.073 0.075 0.074 0.072 0.071 0.067 0.070 0.067N/A N/A 0.089 0.092 0.094 0.093 0.089 0.086 0.086 0.084 0.079 0.077 0.072 0.076 0.072
0.090 0.087 0.087 0.093 0.094 0.089 0.079 0.074 0.074 0.074 0.075 0.075 0.072 0.074 0.0700.085 0.089 0.092 0.097 0.099 0.091 0.086 0.083 0.086 0.081 0.076 0.071 0.069 0.073 0.0720.081 0.081 0.083 0.087 0.091 0.089 0.084 0.076 0.078 0.076 0.076 0.072 0.068 0.073 0.0700.079 0.076 0.078 0.082 0.088 0.083 0.077 0.071 0.074 0.073 0.071 0.069 0.067 0.069 0.0660.079 0.077 0.077 0.079 0.081 0.076 0.073 0.070 0.072 0.071 0.070 0.068 0.066 0.067 0.0650.072 0.070 0.072 0.074 0.076 0.072 0.069 0.066 0.070 0.070 0.070 0.067 0.063 0.062 0.0610.090 0.083 0.087 0.091 0.097 0.086 0.080 0.075 0.079 0.075 0.074 0.072 0.071 0.074 0.0700.086 0.085 0.087 0.091 0.095 0.089 0.086 0.081 0.082 0.077 0.073 0.069 0.069 0.075 0.0730.082 0.080 0.081 0.083 0.085 0.079 0.074 0.071 0.076 0.074 0.071 0.068 0.067 0.072 0.0690.090 0.086 0.087 0.084 0.087 0.083 0.084 0.080 0.082 0.080 0.077 0.074 0.069 0.069 0.0630.094 0.089 0.089 0.092 0.093 0.089 0.086 0.084 0.085 0.079 0.078 0.075 0.071 0.071 0.0680.105 0.096 0.098 0.096 0.094 0.089 0.087 0.089 0.089 0.079 0.075 0.075 0.083 0.083 0.0780.084 0.080 0.084 0.083 0.087 0.084 0.082 0.078 0.079 0.077 0.076 0.072 0.068 0.068 0.0650.097 0.091 0.087 0.092 0.095 0.094 0.091 0.089 0.090 0.085 0.082 0.082 0.084 0.085 0.0810.098 0.094 0.091 0.085 0.084 0.080 0.079 0.085 0.090 0.089 0.079 0.076 0.075 0.079 0.0800.086 0.081 0.081 0.083 0.088 0.081 0.071 0.065 0.069 0.072 0.071 0.068 0.063 0.067 0.0650.098 0.092 0.092 0.090 0.094 0.090 0.088 0.085 0.091 0.086 0.084 0.077 0.075 0.076 0.075
3-Year 4th Max. Average
NOx SIP Call 2003 start
Future challenge?
• EPA on court-ordered schedule to revisit and revise, if appropriate, the ozone standard – Proposal due by Dec. 1, 2014
– Final due by Oct. 1, 2015
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Déjà vu all over again
• In June 2014, CASAC re-recommended: – Revised ozone primary health standard in range
of 60 – 70 ppb
– Revised ozone secondary ozone welfare standard of longer term to protect vegetation
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How states develop ozone strategies
• Fuss with emission inventories for modeling • Run air quality models over and over and
over again assuming some level of control on various source sectors
• Eventually, make across the board cuts in emissions until model approaches standard
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What about the future of NOx strategies?
• Do air quality planning models adequately capture real-world response to control strategies?
• Do we know where we are on the NOx “hump” for strategy effectiveness?
• Are day-to-day changes in NOx important? – Do ozone season NOx programs need adjusting
for daily emissions?
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Are there real-world experiments to poke at these questions?
1. Tier 3 low sulfur gasoline? 2. High electric demand days? 3. Turning on/off power plant NOx controls?
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Tier 3 low sulfur gasoline
• Lowering gasoline sulfur content from 50 ppm to 10 ppm by 2017
• Estimated ~25% immediate NOx reduction from existing gasoline highway vehicles
• Mobile sources largest urban NOx source sector
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High electric demand days
• Annual power plant NOx emissions have greatly decreased over the years, but…
• Day-to-day and hourly power plant NOx emissions can be highly variable
• High electric demand days (e.g., hot & sunny) have highest power plant NOx emissions
• Can be worst ozone days, too
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Daily power plant NOx – model default
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2002 New Jersey-Specific Modeled EGU NOx Emissions Profile
0
100
200
300
400
500
600
700
800
1-Jun3-J
un5-J
un7-J
un9-J
un
11-Ju
n
13-Ju
n
15-Ju
n
17-Ju
n
19-Ju
n
21-Ju
n
23-Ju
n
25-Ju
n
27-Ju
n
29-Ju
n1-J
ul3-J
ul5-J
ul7-J
ul9-J
ul
11-Ju
l
13-Ju
l
15-Ju
l
17-Ju
l
19-Ju
l
21-Ju
l
23-Ju
l
25-Ju
l
27-Ju
l
29-Ju
l
31-Ju
l
2-Aug4-A
ug6-A
ug8-A
ug
10-A
ug
12-A
ug
14-A
ug
16-A
ug
18-A
ug
20-A
ug
22-A
ug
24-A
ug
26-A
ug
28-A
ug
30-A
ug1-S
ep3-S
ep5-S
ep7-S
ep9-S
ep
11-S
ep
13-S
ep
15-S
ep
Day
Mod
eled
var
iabi
lity
of E
GU
NO
x em
issi
ons
(tons
)
Daily power plant NOx – actual (CEMS)
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Are we missing something on peak days?
• Distributed generation? – Small sources (i.e., 500 kW diesel engines) in
emergency demand response programs – Uncontrolled for NOx – Rarely called upon, but can operate on
“emergency” days when peak load high – Info on specific locations and use not publicly
available
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Flipping the switch on power plant NOx controls
Use of power plant NOx controls
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NOx SIP Call 2003 start
Figure from NJ DEP based on EPA CAMD data
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Summary of Challenges 1. Making progress, but so is the health
science
2. Are the models adequately capturing impacts of strategies?
3. Are seasonal NOx programs addressing shorter term ozone events?
4. Future climate?
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Perturbations to the system?
i. Tier 3 low sulfur gas introduction?
ii. NOx emissions on high electric demand days?
iii. On/off power plant NOx controls?
