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Air Emissions Factors and Quantification

New and Revised Emissions Factors for Flares and New Emissions Factors for Certain Refinery Process Units and Determination for No Changes to VOC Emissions Factors for Tanks and Wastewater Treatment Systems

Background

EPA has finalized certain actions in compliance with a consent decree entered into with Air Alliance Houston, Community In-Power and Development Association, Inc., Louisiana Bucket Brigade and Texas Environmental Justice Advocacy Services (“Plaintiffs”). Air Alliance Houston, et al. v. McCarthy, No. 1:13-cv-00621-KBJ (D.D.C.). The consent decree resolves litigation in which Plaintiffs alleged that EPA failed to perform nondiscretionary duties pursuant to Clean Air Act (CAA) section 130 to review, and, if necessary, revise the emission factors for volatile organic compounds (VOC) for flares, liquid storage tanks (“tanks”), and wastewater collection, treatment, and storage systems (“wastewater treatment systems”) at least once every three years. Under the terms of the consent decree, by April 20, 2015, EPA reviewed and either finalized revisions to the VOC emissions factors for flares, tanks and wastewater treatment systems under CAA section 130, or finalized a determination under CAA section 130 that revision of these emissions factors is not necessary.

Final Actions

EPA has evaluated all of the data collected during the 2011 Refinery Information Collection Request (ICR), the data referenced in the Complaint, other test data available to the Agency for flares, tanks and wastewater treatment systems, and data submitted during the public comment period. Based on this evaluation, we have finalized a new VOC emissions factor for flares. We are also finalizing emissions factors (or emissions estimation methodologies) for certain refinery operations and pollutants that are not covered by the consent decree. We have updated Sections 5.1, 8.13, and 13.5 of AP-42 to incorporate the following new and revised emissions factors.

Emission Sources Pollutants
Flares VOC, CO (revised)
Sulfur Recovery Units NOx, CO, THC
Catalytic Reforming Units THC
Hydrogen Plants NOx
Fluid Catalytic Cracking Units HCN

We previously developed a refinery emissions estimation protocol in response to a Data Quality Act petition which was used in the 2011 Refinery ICR. The refinery emissions estimation protocol lists and ranks available methods for calculating emissions from refineries. We are not requiring the use of the Refinery Protocol, just as we do not require the use of AP-42. It is simply another tool for use in estimating emissions when site-specific test data do not exist or are not available. We consider the Refinery Protocol to provide site-specific emissions inventory guidance that will result in more accurate and complete emissions inventories. Therefore, we are finalizing proposed revisions to the Refinery Protocol, with some changes to address specific comments. Specifically, we have updated Sections 1, 5, and 6 of the refinery emissions estimation protocol with these new emission factors.

Based on our review of the available emissions data for tanks and wastewater treatment systems, we found that the available data did not support a finding that revisions to existing emissions estimation methods for those sources was necessary. The data reviewed generally showed adequate agreement between measured data and the existing emissions estimation methods. Therefore, the agency is finalizing its determination that revisions of the VOC emissions factors for tanks and wastewater treatment systems are not necessary.

Based on our review of NOx emissions data for flares and additional information received after proposal, we have determined that the data was not adequate to support revising the NOx emissions factor for flares. Based on comments received, EPA determined that the NOx data used for the proposal contained certain flaws that rendered the data quality suspect.

Supporting Documents for Final Actions

As noted above, based on our review of the reports cited by the Plaintiffs in their complaint, other available test data for flares, tanks and wastewater treatment systems, and information submitted with the public comments, we have developed a new VOC emission factor for flares. We have also concluded that no revision is necessary to the VOC emission factors for tanks and wastewater treatment systems because the available emissions data for tanks and wastewater treatment systems are not adequate to allow for revisions to existing emissions estimation methods for those sources. A report describing the review of these documents and the basis for our findings is available by clicking on the following link:

EPA Review of Available Documents and Rationale in Support of Final Emissions Factors and Negative Determinations for Flares, Tanks, and Wastewater Treatment Systems   April 20, 2015 (PDF 3,438K).

As listed above, we have developed seven new emissions factors and one revised emissions factor in AP-42 based on our review of approximately 200 test reports collected during the 2011 Refinery ICR, development of a peer-reviewed study on Parameters for Properly Designed and Operated Flares, and data submitted during the public comment period. A report that summarizes our review and analysis of these test reports and describes the development of these emissions factors is available by clicking on the following link:

Review of Emissions Test Reports for Emissions Factors Development for Flares and Certain Refinery Operations   April 20, 2015 (PDF 1,060K).

We have finalized three sections of AP-42 to incorporate the revised/new factors. These sections can be accessed at the following links:

We have revised the Refinery Emissions Estimation Protocol to incorporate the revised/new factors, as well as to incorporate a new procedure for estimating emissions from delayed coking units:

Final Emissions Estimation Protocol for Petroleum Refineries - Version 3.0 posted April 20, 2015.

Response to Comments

Response to Comments Document   (PDF 1442 K) posted April 20, 2015.

Below is a link to written comments and questions received:

Comments and Questions as of December 22, 2014   (PDF 61,760K).

Below is a link to view comment attachments that could not be included in the above document:

Attachments to Comments and Questions as of December 22, 2014   (ZIP 11,277K).

Below is a link to view comment attachments that could not be included in the above document:

Additional Information Received After Comment Period   (ZIP 21,360K). 

Settlement Agreement

In response to EPA’s April 20, 2015 final action, on July 10, 2015, Plaintiffs in the original lawsuit filed a petition for judicial review of the final action in the D.C. Circuit Court of Appeals.  Air Alliance Houston, et al. v. EPA, Case No. 15–1210 (D.C. Cir.).  EPA and Petitioners entered into discussions to settle the D.C. Circuit litigation, and on October 13, 2016, published notice in the Federal Register of the settlement agreement reached between the parties. 81 Fed. Reg. 70,677. As part of the settlement agreement, EPA agreed to post certain revisions to Section 13.5 of AP-42 and review 20 Source Classification Codes (SCCs) to determine if they should be included in Tables 13.5-1 and 13.5-2 of AP-42.

Our determination on the SCCs can be found here:

SCC determination Dec 2016 (PDF 68K)

The updated version of AP-42 Section 13.5 can be accessed at the following link:

AP-42 Chapter 13: Miscellaneous Sources Section 13.5 Industrial Flares  

The revisions to Section 13.5 include an update to the VOC emissions factor for flares. The update to the VOC emissions factors is based solely on errors in the original calculation. When we originally calculated the VOC emissions for the Marathon Petroleum Texas City, INEOS, and Texas Commission on Environmental Quality (TCEQ) air-assisted passive Fourier transform infrared (PFTIR) test runs, we inadvertently used the wrong molecular weights for certain compounds. We have corrected this error and have included updated calculations in the background document for Section 13.5, which can be accessed at the above link.

We have also updated Review of Emissions Test Reports for Emissions Factors Development for Flares and Certain Refinery Operations  December 2016 (PDF 903K)