O f f i c e o f A i r Q u a l i t y P l a n n i n g a n d S t a n d a r d s A IR CLEAN OAQPS OAQPS U N I T E D S T A T E S • E N V I R O N M E N T A L P R O T E C T I O N A G E N C Y • Emissions Factors Emissions Factors Improvement Improvement Ron Myers OAQPS/SPPD/MPG 2/13/2008 Revising Critical Revising Critical Components to Components to Streamline and Expand Streamline and Expand Program Applicability Program Applicability
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Emissions Factors Improvement Ron Myers OAQPS/SPPD/MPG 2/13/2008 Revising Critical Components to Streamline and Expand Program Applicability.
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Revising Critical Components to Revising Critical Components to Streamline and Expand Program Streamline and Expand Program
Applicability Applicability
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EF Program BackgroundEF Program Background
Dates to about 1968 (68 pages)Managed by a small staff (5 to 15)Highly variable and declining fundingSteadily increasing demandsPrimarily uses secondary dataReevaluated program in 2003
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Presentation TopicsPresentation Topics
EF Uncertainty Analysis The Electronic Reporting ToolWeb FIRE
Existing EF quality ratings are based on subjective assessments
Everyone uses only the averageNo one considers the accuracy of
their estimate or the potential implications
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BackgroundBackground Stakeholders, National Academy of Sciences,
and the Office of Inspector General (www.epa.gov/oig/reports/air.htm) said EPA should better quantify the uncertainty of the emissions factors
Current Emissions Factors:– Developed using the mean, usually with few available data– Use a subjective letter system for rating quality
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Factor Data Uncertainty StudyFactor Data Uncertainty Study
We assessed statistically the uncertainty in the best emissions factors in AP-42
Criteria for selection of emissions factors:– data quality (A-rated)– data quantity > 15 emissions tests – number/type of pollutants – accessibility of supporting emissions
data
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Emissions Factor DataEmissions Factor Data
We selected 44 A-rated data sets from:– Wood Residue Combustion
Best rated emissions factors had:– Log normal or Weibull distributions (not
normal distributions)
– More tests (with 3 runs per test) reduce uncertainty, diminishing returns on uncertainty after 10 tests
– Uncontrolled HAPs show the greatest variability
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Range of Emissions EstimatesRange of Emissions Estimates
0 0.5 1 1.5 2 2.5 3 3.5 4
E Rated Factor
C Rated Factor
A Rated Factor
D Rated Factor
B Rated Factor
Single Test
Test & Monitor
CEMS
10% 90%25% 75%
Box & Whisker Percentiles
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Next StepsNext Steps
Presentation on study available at: http://www.epa.gov/ttn/chief/efpac/uncertainty.html
The comment period has closed and we are reviewing comments and may revise the report for publication.
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The Electronic Reporting Tool (ERT)The Electronic Reporting Tool (ERT)
Replaces paper source test reports– Uses Microsoft Access– Test Plan development– Test Plan evaluation– Imports field data from Excel– Stores lab data– Test reviewer component– Exports critical data to WEB FIRE
Capabilities of ERTCapabilities of ERTCurrent Pollutants
– Metals – Halides– PM – THC– SOx – NOx
Future Pollutants– Dioxins – POM/PAH
http://www.epa.gov/ttn/chief/ert/ert_tool.html
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Products of ERTProducts of ERT
Improved documentation for evaluation of source test report
Export of critical values and documentation for use in Emissions Factors development in WebFIRE
Export of critical information into data flows for other program areas.
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What is WEBFIREWhat is WEBFIRE WebFIRE (Factor Information Retrieval System) is an internet
based Cold Fusion application that combines AP-42, the Compilation of Air Pollutant Emission Factors, and FIRE.
WebFIRE is used by local, state, and federal agencies, environmental consultants and others who require emissions factor information for estimating criteria pollutants and air toxic emissions from stationary sources & area sources.
WebFIRE will display included and revoked EF’s for all EF available in AP-42 Compilation of Air Pollutant Emission Factors (AP-42 Fifth Edition).
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Benefits of WEBFIREBenefits of WEBFIRE
Updates can be made more frequently, keeping pace with updates to AP-42.
Allows for the addition of new source category codes (SCCs) and emissions factors for use in the EPA’s National Emission Inventories.
Replace the traditional report format of AP-42. AP-42 text will be the same, but the EF tables will be available in WEBFIRE.
Enable the Agency to update, revise, and revoke emission factors on a more real time basis rather than updating factors annually.
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Future Upgrades to WEBFIREFuture Upgrades to WEBFIRE
WebFIRE will have links to emission factor source test reports and supporting background reports to the database.
We have a spreadsheet that can be used in lieu of the ERT to allow users to manually extract info. from the source test reports and be imported into WebFIRE.
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Future Upgrades to WEBFIREFuture Upgrades to WEBFIRE
With this new linkage between emission test reports and emissions factors, WEBFIRE will gain the ability to calculate emissions factors on the fly.
WebFIRE will incorporate emission test results from the ERT or spreadsheet to allow users to tailor their emissions estimate using data selected from facilities that are more representative of their facility.