Improving the Emissions Inventory

Brad Toups, Manager

Industrial Emissions Assessment

August 12, 2004

Regulatory Forum

TexAQS 2000

• The 2000 Texas Air Quality Study provided new insights into factors affecting air quality, including:– Better understanding of plume

characteristics…

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TexAQS 2000

The 2000 Texas Air Quality Study provided new insights into factors affecting air quality, including:– Better understanding of plume characteristics– Better understanding about NOx and

VOCs on Ozone Formation…

Ozone Formation

• Ozone is produced faster and yields more in Houston than in other cities.

– The rapid formation and high ozone yield occur in the industrial plumes downwind of petrochemical facilities.

– Formation rates and yield downwind of the power plants and the city core are comparable to other cities.

TCEQ/TAD BreitenbachMichael Trainer

VOC Measurements

• The VOC concentrations in Houston are very different from other cities.

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– Ethylene concentrations in Houston are much higher than in other cities.

– Ethylene is a highly reactive VOC produced in petrochemical facilities as an intermediate product in plastics production.

– Other highly reactive VOCs such as Ethylene, propylene, Butene and Butadiene are also produced in Houston.

Ethylene Distributions – Log Scale

1.0

2.5

5

10

20

40

60

80

90

95

98.0

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Ethylene (ppbv)

HoustonDallasNashvilleAtlanta

99.9

• The Maximum ethylene levels are an order of magnitude or more higher in Houston

• The ethylene distribution in Houston is approximately log-normal, suggesting continuous emissions.

• Ethylene emissions are definitely not Bimodal; there is no evidence to suggest two separable populations (upsets)

Parrish, 2002

TexAQS 2000

The 2000 Texas Air Quality Study provided new insights into factors affecting air quality, including:– A better understanding of plume characteristics– A better understanding about NOx and VOCs

on ozone formation– That there is more VOC in the atmosphere

than can be accounted for in the Inventory…

Inferred vs Reported Olefin Emissions

0 10 20 30 40 50

West Ship Channel 2

West Ship Channel 1

West Central Ship Channel

East Central Ship Channel

East Ship Channel

Baytown

Channelview

Mont Belvieu

Bayport

Olefin Emissions (Tons/Day)Reported Emissions Inferred Emissions

12.93

2.2

1.8

14.06

5.8

7.5

2.3

1.2

2.1

Ratio

Inferred vs Reported Olefin Emissions

Based upon Auto GC Data

Estes

Ratio

VOC Emissions

• Actual VOC emissions are much greater than reported in the Emissions Inventory

– Aircraft measurements of VOC and NOx indicate that VOC concentrations are up to an order of magnitude larger than inventory reported emissions.

– High VOC concentrations occur 40-60% of the time in industrial areas, indicating that these VOC releases are not rare occurrences, but relatively frequent events.

– Either upsets are much more frequent than reported, or there are far more leaks than currently estimated.

TexAQS 2000

The 2000 Texas Air Quality Study provided new insights into factors affecting air quality, including:– A better understanding of plume characteristics– A better understanding about NOx and VOCs

on ozone formation– That there is more VOC in the atmosphere than

can be accounted for in the Inventory

Adjusted VOCs Generate More Ozone and Improve Model Performance

Box model with adjusted ratios of ethylene and propylene to NOx reproduces the ozone measured by the aircraft quite well

Trainer, 2001

Why do we need to improve the Emissions Inventory?

• We need to put the correct meteorological data and correct emissions data into the model

• So the model can give us the right answers

for the right reasons

• So we can develop effective policies

to control ozone

Inventory Improvement GoalsAccuracy and Completeness

• Correct census of sources

• Location and physical characteristics of the Facility, Control Device, Emission Point

• Chemical speciation under all conditions

• Chemical quantification under all conditions

Complete Census

• Working towards a database to capture allowable emissions from all authorization mechanisms

Physical Characteristics of FIN, CIN, EPN

Physical Characteristics (con’t)

Before aerial photo

After Aerial Photo

Inferred vs Reported Olefin Emissions

0 10 20 30 40 50

West Ship Channel 2

West Ship Channel 1

West Central Ship Channel

East Central Ship Channel

East Ship Channel

Baytown

Channelview

Mont Belvieu

Bayport

Olefin Emissions (Tons/Day)Reported Emissions Inferred Emissions

12.93

2.2

1.8

14.06

5.8

7.5

2.3

1.2

2.1

Ratio

Inferred vs Reported Olefin Emissions

Based upon Auto GC Data

Estes

Ratio

Inventory Improvement GoalsAccuracy and Completeness

• Correct census of sources

• Location and physical characteristics of the Facility, Control Device, Emission Point

• Chemical speciation under all conditions

• Chemical quantification under all conditions

Chemical speciation under all conditions

• Developing Statistical Tools to:– identify mix and proporation of contaminants per SCC

• Matching Permit Representations with respect to speciation

• We have and continue to require the most accurate, up to date assessment techniques

• Integrating Emissions Events information into EI reviews

Inventory Improvement GoalsAccuracy and Completeness

• Correct census of sources

• Location and physical characteristics of the Facility, Control Device, Emission Point

• Chemical speciation under all conditions

• Chemical quantification under all conditions

Chemical quantification under all conditions

• Particularly with VOCs,– Some VOC components (like ethylene) are highly

reactive, others contribute less to ozone formation

– We need measurements of the composition of the VOC emissions from various industrial processes.

• Will continue to challenge inappropriate use of emissions factors when better information is available

• Will insist on consistency with EI Guidelines

Potentially Underreported Sources

• Focus on VOCs:

– Fugatives– Cooling Towers– Flares– Wastewater Systems

Risk Based Approach

• Statistical Tool development– Will continue to develop more tools to identify

discrepancies in reported data

• Risk Based closer review of selected sites

• Appropriate enforcement to encourage Responsible Official to assure reported emissions are accurate and complete

Emissions Inventory Improvements

• Benefits:– Form a solid foundation for air quality planning– Help to characterize rule effectiveness for

controlling emissions– Provide increased assurance to the Public about

sources of emissions and emissions trends– Provide a sound basis for emissions fee

assessments– Reduce reliance on ‘factors’ in modeling

Resources

• Emissions Inventory Rules and Guidance– http://www.tnrcc.state.tx.us/air/aqp/psei.html

• Emissions Inventory Helpline– 512 239-1773

• TexAQS Study Information– http://www.utexas.edu/research/ceer/texaqsarchive/

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