AWMA Annual Conference June 16-19, 2009
Paul Complin1, Robert Lyng 2,
Hong Liu 3, Alan Cocks4
1ORTECH Environmental, [email protected] Ontario Power Generation Inc., [email protected]
3 PhD Candidate, York University, [email protected] EnviroAnalytics, [email protected]
Application of Two State-of-the-art
Dispersion Models
AWMA Annual Conference June 16-19, 2009
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Ontario Regulation 419/05 under the Ontario Environmental Protection Act introduced new air requirements including updated air dispersion models.
New Ontario Air Regulatory RegimeNew Ontario Air Regulatory Regime
AWMA Annual Conference June 16-19, 2009
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All Ambient Air Criteria Met for current Regime
But Preliminary Screening Indicated Potential for Hundreds of Hours of Exceedances
SO2 selected as the basis for assessing compliance risk.
Compliance IssueCompliance Issue
AWMA Annual Conference June 16-19, 2009
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Develop a Risk Based Operational Regime that meets the new Requirements– Operational Restrictions– Fuel Switching– Capital Upgrades (e.g. FGD)
Overall ProjectOverall Project
AWMA Annual Conference June 16-19, 2009
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SO2 selected as the basis for assessing compliance risk.
AERMOD and ADMS selected as the Assessment Models
Modelling ProjectModelling Project
AWMA Annual Conference June 16-19, 2009
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– Eight Coal Fired Power Generation Units– Range of coal types and blends– Two 200 metre stacks with four flues each– CEMs measure SO2 emission rates, exhaust
velocities, exhaust temperatures– Lakeshore site, flat terrain
Nanticoke Generating StationStation
AWMA Annual Conference June 16-19, 2009
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Lake Erie
Lake Ontario
Nanticoke GS
Buffalo
Toronto
Detroit
AWMA Annual Conference June 16-19, 2009
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AWMA Annual Conference June 16-19, 2009
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Regulation 419/05 and the Air Dispersion Modelling Guideline for Ontario
• Issued in 2005, updated March 2009• Screen3/AERMOD as the primary model• Regional 5 year Meteorological Data Sets• Highest 8 hours Excluded as Outliers• Alternate Models ‘If Conditions Warrant’
Modelling ProtocolModelling Protocol
AWMA Annual Conference June 16-19, 2009
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AERMOD PerformanceAERMOD Performance
1
10
100
1000
1 10 100 1000
Ambient SO2 (ug/m3)
Mo
dell
ed
SO
2 (
ug
/m3)
Unpaired Q-Q
1/1 lineX2 line
/2 line
AWMA Annual Conference June 16-19, 2009
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Modelling MethodologyModelling Methodology
Ambient SO2
Operational conditions(8 units @ variable loads)
Sulphur Contents of Coal Blends
Continuous Emission Monitor
Data(Flow,
Temp, SO2)
SO2 Emission Inventory
Flow Rate(function of
GEO);Temperature
MOE 5 Year Meteorology
Set
AERMODfollowingADMGO:
ADMS with identical inputs
Understand Model
Performance
Assess Risk Factors(AAQC)
Develop Risk Based Operational
Regime
AWMA Annual Conference June 16-19, 2009
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Two Models: AERMOD & ADMSTwo Models: AERMOD & ADMS
AERMOD ADMSBoth “New Generation” models
Components are based on similar sets of state-of-the-art algorithms to describe the state of atmospheric boundary layer
Bimodal distribution of turbulent vertical velocities for convective conditions.
Regulatory model in US & Ontario and Alternative model elsewhere.
Regulatory model in UK and Alternative model in US.
Allows vertical profiles of wind and temperature to be input.
Requires only one level of near-ground observations to be input, but could take the state of the art ABL as input.
Contains shoreline module.
AWMA Annual Conference June 16-19, 2009
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Dispersion Factors for Five ScenariosDispersion Factors for Five Scenarios(all units at MCR)(all units at MCR)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
1 10 100 1000 10000
Number of Hours within 5-Year (1996 - 2000)
Ho
url
y D
isp
ersi
on
Fac
tor
(ug
/m3/
g/s
)Sc 1 AERMOD
Sc2 ADMS4 with AERMET Data
Sc3 ADMS4
Sc4 ADMS4 Coastal - Water Temperature
Sc5 ADMS4 Coastal - Air Temperature
AWMA Annual Conference June 16-19, 2009
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Key Model ParametersKey Model Parameters
Monin-Obukhov Length Boundary Layer Depth
-1.2
-0.8
-0.4
0
0.4
0.8
1.2
-1.2 -0.8 -0.4 0 0.4 0.8 1.2
ADMS4 1/Lmo(m-1)
AERM
ET 1
/Lm
o(m
-1)
0
1000
2000
3000
4000
5000
0 1000 2000 3000 4000 5000
ADMS4 bl height (m)AE
RMET
bl h
eigh
t (m
)
y
AWMA Annual Conference June 16-19, 2009
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Wind Speed versus Dispersion FactorWind Speed versus Dispersion Factor
1
3
5
7
9
11
13
15
17
19
21
0.06 0.11 0.16 0.21 0.26
Hourly Dispersion Factor (ug/m3/g/s)
Win
d S
pe
ed
(m
/s)
AERMOD
ADMS4
AWMA Annual Conference June 16-19, 2009
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1/L1/Lmomo versus Dispersion Factor versus Dispersion Factor
-0.6
-0.4
-0.2
0
0.06 0.11 0.16 0.21 0.26
Hourly Dispersion Factor (ug/m3/g/s)
1/L
mo(m
-1)
AERMOD
ADMS4
AWMA Annual Conference June 16-19, 2009
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Model ParametersModel Parametersfor 1000 highest Maximum Dispersion Factorsfor 1000 highest Maximum Dispersion Factors
Monin-Obukhov Length Boundary Layer Depth
-0.6
-0.2
0.2
0.6
1
-0.6 -0.2 0.2 0.6 1
ADMS 1/Lmo (m-1)
AER
MET
1/L
mo
(m-1
)
0
1000
2000
3000
4000
5000
0 1000 2000 3000 4000 5000
ADMS bl height (m)
AEM
ET b
l hei
ght (
m)
AWMA Annual Conference June 16-19, 2009
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Dispersion Factors for Five ScenariosDispersion Factors for Five Scenarios(all units at MCR)(all units at MCR)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
1 10 100 1000 10000
Number of Hours within 5-Year (1996 - 2000)
Ho
url
y D
isp
ersi
on
Fac
tor
(ug
/m3/
g/s
)Sc 1 AERMOD
Sc2 ADMS4 with AERMET Data
Sc3 ADMS4
Sc4 ADMS4 Coastal - Water Temperature
Sc5 ADMS4 Coastal - Air Temperature
AWMA Annual Conference June 16-19, 2009
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ConclusionsConclusions
• Two state-of-the-art models were applied in compliance mode to assess their differences.
• The models' different treatment of key model parameters results in significantly different outputs.
• The identification of the compliance parameters, and therefore the cost of compliance, can be strongly influenced by model selection.
• ADMS offers a shoreline module whereas AERMOD currently does not. This difference may be important for facilities near large bodies of water.
AWMA Annual Conference June 16-19, 2009
Paul G. Complin
Principal- Compliance and Permitting
ORTECH Environmental
804 Southdown Road
Mississauga, ON, Canada L5J 2Y4
Phone 905 822-4120 e266 or 877-774-6560 e266
Fax 905 855-0406
[email protected] www.ortech.ca
Questions?
