Achieving Emission Reductions
Emission reductions that qualify as emission credits may be achieved by a number of means, including but not limited to installation of control equipment, changes in process inputs, formulations, products, product mix, or raw materials, reductions in actual emission rates, reductions in operating hours, production curtailment, shutdown of emitting sources or facilities in certain circumstances, or any other enforceable method as approved by the department or adopted as a rule by the board.
Calculating Emission Reductions
The following methods are acceptable for calculating the quantity of emission reductions:
- AP-42 Compilation of Air Pollutant Emission Factors
- Stack Test
- Continuous Emissions Monitoring System (CEMS)
- Other approved methods
Note: AP-42 is the recommended source of air pollutant emission factors for both criteria and toxic emissions.
Modification
Modifications typically include the following: installation of control equipment; changes in process inputs, formulations, products, product mix, or raw materials; reductions in actual emission rates; and reductions in operating hours. To calculate the amount of emission reduction that can be quantified as an emission credit from a modification:
- Calculate the average actual annual emissions prior to emission reduction using data from the 24 month period immediately preceding the reduction in emissions (The Indiana Department of Environmental Management (IDEM) may allow the use of a different time period upon a determination that such period is more representative of normal source operation.)
- Calculate the annual emission rate following reduction
- Subtract the annual emissions rate following the reduction from the average actual annual emissions prior to the reduction
Curtailment
Reductions are calculated differently for production curtailment and shutdown of emitting sources or equipment. To calculate the amount of emission reduction that can be quantified as an emission credit from a curtailment:
- Calculate the average actual annual emissions prior to curtailment using data from the 24 month period immediately preceding the reduction in emissions (IDEM may allow the use of a different time period upon a determination that such period is more representative of normal source operation.)
- Calculate the allowable annual emission rate following curtailment
- Subtract the allowable annual emissions rate following the curtailment from the average actual annual emissions prior to the curtailment
Pollutants That May Be Registered
Emission reductions from any regulated air pollutant for which the United States Environmental Protection Agency (U.S. EPA) has established a National Ambient Air Quality Standard may be registered in the Emission Credit Registry. The criteria air pollutants are carbon monoxide (CO), lead (Pb), particulate matter with a diameter less than 10 microns (PM10), particulate matter with a diameter less than 2.5 microns (PM 2.5)*, nitrogen oxides (NOX), ozone (O3), and sulfur dioxide (SO2). Since ozone is a secondary pollutant, emission reductions must be quantified with the precursor pollutants, volatile organic compounds (VOC) or nitrogen oxides (NOX).
Currently, Indiana has areas of nonattainment for NAAQS for 8-hour Ozone and Fine Particulate Matter (PM2.5).
* Until U.S. EPA adopts specific New Source Review (NSR) rules for PM2.5 emissions, it has directed states to regulate PM10 emissions as surrogate for PM2.5 emissions; therefore, all PM reductions will be listed as PM10 in the Emission Credit Registry.
Hazardous air pollutants may only be registered as VOC or PM10 since the NSR rules do not include a provision for offsetting HAP emissions.
Submissions Into the Emission Credit Registry
Sources must submit an application to list credits in the Emission Credit Registry. Data cannot be added to the Emission Credit Registry until the appropriate permits have been modified through the normal permit review process. The reduction becomes permanent when the source generating the emission credits receives its air permit. In most cases the source will need to obtain a permit modification to make the emissions reductions permanent. If the source will be adding one or more control devices to reduce emissions, a source modification is required. If the source does not have such a permit, it will need to apply to modify the current operating permit. Find information about the application process and contact IDEM for assistance.
Permit Review to Submit Reductions into the Emission Credit Registry
Upon receipt of a complete Emission Credit (EC) Registry application and issuance of the appropriate permit (or source) modification, IDEM will:
- Review each Emission Credit Registry application and determine whether the emission reduction meets the criteria for inclusion in the Emission Credit Registry;
- Enter data for each verified emission credit into the Emission Credit Registry; and
- Notify the permitted source in writing of IDEM 's action.
- Post the information about potentially available credits on the Emission Credit Registry website.
Approval Time
If all of the appropriate permitting approvals have been issued* and the application is complete, you can expect to receive a confirmation letter from IDEM regarding the registration or update to your amount of registered credits in 60 days. The information should be posted to the website shortly after issuance of the letter, usually within one week.
* Time periods for the approval of permit modifications (or source modifications) are established in 326 IAC 2, and may take up to 120 or 270 days, depending on the level of review required.
Sources may submit concurrent applications. For example, a source may wish to submit emissions reductions for inclusion in the Emission Credit Registry and at the same time apply to have a portion of those emission credits withdrawn from the Emission Credit Registry for internal use. Likewise, a source may have already agreed to sell a portion of the emission credits they are generating so the source using those credits may wish to submit the application to use the emission credits at the same time the generating source applies to have them added to the Emission Credit Registry. If a situation like this occurs, IDEM recommends that the application to use the emission credits reference the pending application to submit the emission reductions. Since the emission credits are not truly available until the modification creating the permanence of the emission reductions is issued, the permit action that results in withdrawal of the credits may need to be placed on hold until the first permit is issued.
Eligibility to Register Emission Reductions
Permitted sources and air permit applicants may use the Emission Credit Registry. Any permitted source may apply to register emission credits of any regulated pollutant, and any source seeking a permit for a new or modified source obtain credits from sources listed in the Emission Credit Registry.
Mobile Sources Are Not Eligible
At the present time, the registration of emission reductions that qualify as emission credits is limited to stationary point sources.
Is There A Deadline for Registering Emission Reductions?
There is no deadline for registering emission credits; however, emission credits are no longer usable after they are five years old (plus time for construction).
Data Timeframe
The Emission Credit Registry was created on June 15, 2004. All emission reductions created on or after this date, and emission reductions generated up to five years prior to this date may be submitted for inclusion in the Emission Credit Registry.
Submission of Confidential Records
All information submitted to IDEM will be made available to the public unless it is submitted under a claim of confidentiality. To prevent the public disclosure of confidential business information or trade secrets, be certain that you mark the information and include a confidentiality claim with your submittal.
For more information on confidentiality for certain types of business information, please review IDEM's Nonrule Policy Document regarding Emission Data, Air-031 (available on the IDEM Nonrule Policies page).
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