EMVAP –Emissions Variability Processor...Status Report on Development and Testing of the EMVAP...

Status Report on Development and Testing of the EMVAP Systemand Testing of the EMVAP System

EMVAP – Emissions Variability Processor Bob Paine AECOMBob Paine, AECOM

10th EPA Modeling Conference, March 14, 2012

Other contributors:Other contributors:

David Heinold and Rich Hamel, AECOM

El di K i i d N h K EPRIEladio Knipping and Naresh Kumar, EPRI

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Sponsored by

Outline of PresentationOutline of Presentation

• EPA Modeling Guideline proceduresEPA Modeling Guideline procedures

• Nature of variable emissions distributions

• Description of procedures for Monte Carlo analysisDescription of procedures for Monte Carlo analysis approach to handle variable emissions: EMVAP

• Evaluation of EMVAP with 3 AERMOD evaluationEvaluation of EMVAP with 3 AERMOD evaluation databases

• Sensitivity of results to number of simulated yearsy y

• Conclusions

2

EPA Appendix W Modeling Proceduresd l d (f h• Modeled emission rate input (for short‐term

averages) is:

E i i li it ti l l ti f t– Emission limit x operating level x operating factor

(lb/MMBtu) (MMBtu/hr) (hours/year)

– Max. emission x design x continuous

limit capacity operation

• Modeling continuous operation for intermittent sources or maximum emission limits for variable

i i i f ti l l femission sources is of concern, particularly for a probabilistic NAAQS 3

Emission Rate Variability• Large variation possible over the course of a year

• Intermittent sources (e.g., emergency backup engines Intermittent sources (e.g., emergency backup enginesor bypass stacks) present modeling challenges

• For these sources, assuming fixed peak 1‐hour , g pemissions on a continuous basis will result in unrealistic modeled results

• Better approach is to assume a prescribed distributionof emission rates

• EMVAP (Emissions Variability Processor), described below, uses this information to develop alternative

t i di t d l d li i fways to indicate modeled compliance using a range of emission rates instead of just one value

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Example of Hourly Emissions Sequencep y q

Example Emission Cumulative Frequency DistributionFrequency Distribution

(g/s)

mission

rate

Em

% cumulative frequency over all days

Example Emission Cases for EMVAPExample Emission Cases for EMVAP1) <=140 g/s 100% of the time2) <=100 g/s 98% of the time

Peak observed emission rate 133 g/s

(g/s)

2) < 100 g/s 98% of the time3) <= 65 g/s 89% of the time4) <= 40 g/s 84% of the time5) <= 25 g/s 77% of the time6) Off 20 % f h i

= 133 g/s

mission

rate 6) Off 20 % of the time

Weighted average emissionrate = 43.4 g/s, less than 1/3

Em

g/ , /of the peak value

% cumulative frequency over all days7

Approach (“EMVAP”) for Multiple Allowable Emissions ModelingAllowable Emissions Modeling

• Create an emissions frequency distribution

• Model the source with unit emissions (up to 5 “real” years) – different runs maybe needed over a range of h t texhaust parameters

• Create many (e.g. 1,000) simulated annual realizations of conc with random number generator for emission rateconc. with random number generator for emission rate

• Randomly assign an emission rate multiplier for each hour using the source‐specific emissions distributionhour using the source‐specific emissions distribution

• Process summary statistics over each year/receptor

• Use post processing software to add concentrations for• Use post‐processing software to add concentrations for multiple sources plus background

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Random Selection ProcessRandom Selection Process• In some cases, peak emissions occur in groups of hhours

• The form of the 1‐hour NO2 and SO2 standard i l l th hi h t t ti h iinvolves only the highest concentration hour in any given day

• Therefore it is likely conservative to distribute peak• Therefore, it is likely conservative to distribute peak emission rates randomly rather than in groups

• Use of a random selection process such as a Monte• Use of a random selection process, such as a Monte Carlo procedure, is appropriate

• But sources that operate in tandem can be treatedBut, sources that operate in tandem can be treated with the same sequence of random numbers

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Purpose and Definition• The EMVAP system is a probabilistic post‐processor for AERMOD designed to more realistically model emission g ysources against short‐term NAAQS

• The EMVAP system consists of three modules + AERMOD:y

– EMDIST emissions analyzer : aids in determining emission inputs for AERMOD runs

– EMVAP probabilistic emission simulator: used to randomly generate modeled concentrations based on source emissions frequencies

– EMPOST post‐processor: takes EMVAP output and performs statistical analyses, generating modeled concentrations in the form of the NAAQS 10

EMDISTEMDIST

• Statistical Analysis to Aid in Emissions Input to y pEMVAP

• Required InputsTakes in up to 5 years of emissions data in either AERMOD– Takes in up to 5 years of emissions data in either AERMOD input file format or put into EMDIST format (described in read‐me file)

• Optional Inputs• Optional Inputs– If hourly stack exit temperature and velocity data are available, it is used in recommended emission case calculationscalculations

– EMDIST can also import hourly ambient temperature data and report corresponding emission rates and ambient temperature datatemperature data

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EMVAP• Probabilistic Emissions Simulator Post‐processor for AERMOD (used after AERMOD is run for all cases)

• Required Inputs• Required Inputs– Number and list of years included in the analysis– The NAAQS standard for which the EMVAP results are to b dbe compared

– The number of Monte Carlo simulations to perform– File containing the receptors used in the AERMOD runs– Random number file used in generating emissions randomly each hour – sources can be linked with a common sequence of random numbers

– For each of up to 10 source data sets:• The load cases and names of the AERMOD result files • Emission cases and associated frequencies

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EMPOSTEMPOST

• Results Determination and Reporting for EMVAPResults Determination and Reporting for EMVAP

• Required Inputs

– Number and list of years in the analysisNumber and list of years in the analysis

– Name of the file containing receptor coordinates.

The number of modeling iterations performed in– The number of modeling iterations performed in EMVAP and the names of the iteration files

– Definition of statistics to report if desiredDefinition of statistics to report, if desired

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EMVAP EvaluationEMVAP Evaluation

• Selected 3 AERMOD Databases with variety of terrainSelected 3 AERMOD Databases with variety of terrain settings

• Ran AERMOD with both actual and constant peak p(allowable) hourly emissions – got 99th percentile peak daily 1‐hour max pre vs. obs

• Ran EMVAP to get the same result from median value over 1000 simulated years

• Expectation: EMVAP result would be between that of actual and allowable emissions

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Evaluation DatabasesEvaluation Databases

• Lovett Generating Station – complex terrain (Hudson• Lovett Generating Station – complex terrain (Hudson River Valley)

– 1 full year test case 8 monitors1 full year test case, 8 monitors

• Clifty Creek Generating Station – Ohio River gorge

– 1 full year with 3 units with differing load profiles– 1 full year with 3 units with differing load profiles, 6 monitors

• Kincaid Power Station – flat corn fields of IllinoisKincaid Power Station flat corn fields of Illinois

– Partial year case, 1 stack, 28 monitors

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Lovett

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Frequency Distribution of SO2 Emissions at L tt 1988

300

350

Lovett, 1988

250

300

ons (g/s)

150

200

SO2Em

issio

50

100

Hou

rly

0

50

0 10 20 30 40 50 60 70 80 90

Percent of Emissions

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Lovett Generating Station – Exit Velocity vs. Emission Rate

40Residual Plot as a Function of Emissions and Exit Velocity

30

35

20

25

ty (m

/s)

10

15

Exit

Velo

cit

0

5

1.234 - 75 (n = 1053) 75 - 90 (n = 931) 90 - 140 (n = 2502) 140 - 220 (n = 2245) 220 - 255 (n = 448) 255 - 395.806 (n =

E

1.234 75 (n 1053) 75 90 (n 931) 90 140 (n 2502) 140 220 (n 2245) 220 255 (n 448) 255 395.806 (n 433)

SO2 Emission Cases (g/s)18

600

)EMVAP 50th Percentile Results for Lovett Generating Station

450

500

550

ue*) (u

g/m3)

EMVAP results are all much better h i k i i

300

350

400

(Design Va

lu than using peak emissions.

200

250

300

ncen

tration (

50

100

150

1‐hr SO

2Co

n

0

Observed (Monitor)

AERMOD with Actual

Emissions

AERMOD with Maximum Emissions

EMVAP 5‐Case Equal Freq. Distribution

EMVAP 10‐Case Equal

Freq. Di t ib ti


Freq. Di t ib ti

EMVAP 5‐Case Emission Rate Distribution

EMVAP 10‐Case Emission

Rate Di t ib ti


Rate Di t ib ti

1

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Distribution Distribution Distribution Distribution

EMVAP Cases * Design Value is 99th Percentile of the daily maximum 1‐hour average

CliftyCreek

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Frequency Distribution of SO2 Emissions at Clifty Creek Stack 1 1975

3500

4000

Clifty Creek Stack 1, 1975

3000

3500

ons (g/s)

2500

SO2Em

issio

1500

2000

Hou

rly

1000 0 10 20 30 40 50 60 70 80 90 100

f i i

21


Frequency Distribution of SO2 Emissions at Clifty Creek Stack 2 1975

3500

4000


3000

3500

ns (g

/s)

2500

SO2Em

ission

1500

2000

Hou

rly S

1000

1500

0 10 20 30 40 50 60 70 80 90 100

22


Frequency Distribution of SO2 Emissions at Clift C k St k 3 1975

4000


3000

3500

ns (g

/s)

2500

SO2Em

ission

1500

2000

Hou

rly S

1000 0 10 20 30 40 50 60 70 80 90 100

f i i

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15001550160016501700

m3)

EMVAP 50th Percentile Results for Clifty Creek Generating StationEMVAP results are improved over using peak emissions.

1150120012501300135014001450

lue*) (ug

/m

g p

750800850900950100010501100

n (Design Va

400450500550600650700750

oncentration

50100150200250300350400

1‐hr SO

2Co

0

Observed (Monitor)

AERMOD with Actual

Emissions




Freq. Distribution


Freq. Distribution



Rate Distribution


Rate Distribution

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EMVAP Cases * Design Value is 99th Percentile of the daily maximum 1‐hour average

Kincaid

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Frequency Distribution of SO2 Emissions at

13000

q y 2

Kincaid Power Station

9000

11000

ns (g

/s)

7000

O2Em

ission

3000

5000

Hou

rly S

1000

3000

0 10 20 30 40 50 60 70 80 90 100

f i i

26


125013001350

3)EMVAP 50th Percentile Results for Kincaid Generating Station

100010501100115012001250

ue*) (u

g/m3

700750800850900950

(Design Va

lu

400450500550600650

ncen

tration

100150200250300350

1‐hr SO

2Co

n

050

Observed (Monitor)

AERMOD with Actual

Emissions




Freq. Di t ib ti


Freq. Di t ib ti



Rate Di t ib ti


Rate Di t ib ti

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Distribution Distribution Distribution Distribution

EMVAP Cases* Design Value is 99th Percentile of the daily maximum 1‐hour average

Sensitivity Analysis of Design Conc. By Number 3of Iterations Performed – Lovett (g/m3)

Iterations 50th 75th 90th Max.

50 348.99 374.81 413.85 458.40

500 347.32 374.81 412.31 460.45500 347.32 374.81 412.31 460.45

1000 347.32 374.81 412.31 534.39

2500 347.32 374.81 412.31 541.62

5000 347.32 374.81 412.31 614.7828

Current Limits in EMVAPCurrent Limits in EMVAP

• Receptors: no effective limit (tested so far with p (10000 receptors)

• Source groups to be combined: 10 (can include h b k d)groups with constant emissions, or background)

• Load cases per source group: 20It ti 5000 i l t d• Iterations: 5000 simulated years

• Years of modeled data per iteration: 5

Typical run time is a few minutes to an hour on a standard computing platform.standard computing platform.

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Conclusions and StatusConclusions and Status

• EMVAP is currently operational for EPRI beta testingEMVAP is currently operational for EPRI beta testing and consideration of implementation approaches

• Evaluation against field data shows expected results: g pcritical predictions are somewhat higher than those from actual emissions and lower than those from peak emissions

• Further development and testing is currently d bunderway by EPRI

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EMVAP –Emissions Variability Processor...Status Report on Development and Testing of the EMVAP...

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