Depending upon the level of emissions and the type of permit being sought, you may need to submit an environmental model.
• If you seeking a PSD or Title V permit, you will be preparing an environmental model and submitting the results as part of your permit application.
• Generally if you are seeking a Synthetic Minor / Non-PSD permit, it is less likely modeling will be required.

While the models have common roots with the models used by the USEPA, there are specifics which vary with the permitting agency, so it is best to start by ascertaining what software they are using and what constants or variables may be applicable to your situation. This isn’t off the shelf software and the modeling isn’t the sort of thing that you do for yourself; you need to engage experts.

No doubt there is an art to modeling; there is no single right answer, several iterations will be required to arrive at optimal results.

The best bet before commencing modeling is to talk to the permitting authority having jurisdiction for your project, before proceeding with significant work on the project.

Contact IEA and one of our experts will assist you with the environmental permitting process.

Modeling Considerations

The following issues impact modeling results:
• What are the existing emissions from your facility?
• How will the new emissions impact your existing permits?
• What is your fuel source?
• How close are emission points to your property line?
• How tall are your emission stacks?
• What is your total potential to emit?
• Can you accept operating constraints? Should those operating constraints be based on operating hours or fuel burned?
• What types of emissions controls (see below) should be incorporated?
• Do you exceed any National Ambient Air Quality Standards (NAAQS)?

Emission Controls

The modeling process, as well as the final inputs to the permitting process are used to evaluate the impacts of emissions controls. Depending on the specific permitting process you will hear two terms:
• Best Available Control Technology (BACT)
• Maximum Achievable Control Technology (MACT)
Both evaluate the cost effectiveness of emissions controls, in part looking at the current technology that has been deployed, the resultant costs per ton to eliminate emissions and whether it is cost effective to mandate these controls for the project. Unfortunately, this is not always as black and white of an issue as project developers would like. A lot depends upon the results of similar projects. The types of emission controls may include:
• Baghouse Filter
• Electrostatic Precipitator (ESP)
• Urea Injection
• Wet or Dry Scrubbers
• Particulate Filters
• Catalytic Filters

Continuous Emission Monitors (CEMs)

Depending on the level and nature of expected emissions, the permitting authority may require the use of a CEM. As a general rule avoiding CEMs is worth the effort; they are expensive to install, expensive to maintain and if they are out of service for any extended periods may require you to shut down your project until they are back in service.