FW: WebFire Uncontrolled Emission Factors Evaluation

Steering Committee,

Some notes from yesterday’s call are up at:

Please note that March 26-27 was selected for the next meeting and it will be in Chicago.

Also, Tom has put together the excellent summary below of where things stand with the emission factor discussion . The attachments are included at the following link. Please review and provide comments.

http://glos.us/wiki/x/BACT

Jon

~~~~~~~~~~~~~~~~~~~

Jon Dettling

734-274-5183

dettling@glc.org

From: Tom Velalis [mailto:tom.velalis@epa.state.oh.us]
Sent: Friday, December 14, 2007 2:54 PM
To: Jon Dettling; 'Airtoxics'
Subject: WebFire Uncontrolled Emission Factors Evaluation

Evaluation of WebFire Uncontrolled Emission Factors

Purpose: Evaluate Uncontrolled WebFire Emission Factors

In last conference call, we had the opportunity to review the assumptions applied in the processing of the WebFire records and discuss the steps for producing emissions factors data sets for evaluation. The participating States agreed to review the questionable emission factors, draw conclusions and make recommendations.

Processing Steps

The main processing steps are outlined below:

SCCs are assigned to Groups based on common material processed and common equipment type.
Only Webfire uncontrolled and un-revoked emission factors are evaluated.
WebFire units, measures, material and action codes are converted to a strandardized set of codes for comparison of emission factors.
Applied AP 42 apendix A default values for formula conversion into factors
Considered only top 64 critical HAPs and two criteria groups (PMs and VOC).

Data Sets

The following Data sets are produced for evaluation:

29 VOC-HAPs
16 PM-HAPs
15 PAHs
6 Misc-HAPs
PM and VOC formulas and emission factors

Cursory Review

Each of the sets is a listing of emission factors that belong to the same groups. In other words, the emission factors that share the same material on column H belong to the same group. A visual evaluation of the numeric values, within each group, is needed to identify possible outliers. For each data set, visual evaluation is performed and questionable records are highlighted in yellow. Each worksheet name with questionable records is also highlighted in yellow. In most cases, an outlier is a value that is different to another value within the same group by a factor of 10.

One exception is the listing of the PM formulas and VOC formulas. Since there are few formulas in Webfire, it is necessary to evaluate all of them. The SCC Groups concept is not applied to those records. For illustration purposes, the formulas are only grouped by processed material.

States are encouraged to go over each worksheet and confirm the highlighted records. An alternative scenario is to only review the existing highlighted records. It should take no more than 2-3 hours to go over the records.

Preliminary Conclusions

There are some bad Fire Entries. Example BENZ(GHI)PE for 10100604
The emission factors for VOC and VOC-HAPs seem to have better consistency within thei respective groups than the PM and PM-HAPs emission factors
The worst inconsistency is observed with the PM formulas and particularly with Coal processes
Many of the sets with questionable numeric factors are based on old confidential reports. Those values do not compare well with newer AP-42 factors. Should we continue using those old factors?
There is pattern with some SCCs that produce inconsistent results for many pollutants.
When comparing the factors within each group, it is important to review the source and quality of emission factors.

State’s Evaluation and Review

This is not a mandatory assignment to the States. However, State’s participation is important for the success of this evaluation. Each State is encouraged to review each worksheet and confirm the identification of questionable records. If time is a factor, States can review only the identified records, yellow highlighted records. The hope is that an agreement can be reached and conclude which factors are bad for inventories.

What’s Next

On next conference call, there will be a discussion on this review.

Begin to compile a listing of bad emission factors and a list of alternative values.

Begin Gap Filling discussion

Attachments:

Priority_Pollutant_List64_VOC_HAPs.xls

Priority_Pollutant_List64_PM_HAPs.xls

Priority_Pollutant_List64_PAHs.xls

Priority_Pollutant_List64_MISC-HAPs.xls

Priority_Criteria_Pollutant_EMISSION FACTOR AND FORMULAs.xls