Knowing the facility-wide potential emissions is a vitally important aspect of determining the air permitting requirements of your facility. As a result, the Kansas Department of Health and Environment (KDHE) now requires the submission of facility-wide potential to emit (PTE) calculations with any permitting submittal, including no-permit-required determinations. KDHE guidance does not explicitly require submittal of facility-wide PTE with all permit applications. It is recent Trinity’s experience, however, that KDHE now requests submittal with every application. KDHE will not process a submittal without a current facility-wide PTE on hand. In short, there has never been a better time to determine your site-wide PTE for the first time or re-visit your existing calculations to ensure they are accurate and up to date. 

What is Potential to Emit (PTE)?

PTE is defined in K.A.R 28-19-200(yy) as: “Potential to emit means the maximum capacity of a stationary source to emit a pollutant under its physical and operational design. Any physical or operational limitation on the capacity of the source to emit a pollutant, including air pollution control equipment and restrictions on hours of operation or on the type or amount of material combusted, stored, or processed, shall be treated as part of its design if the limitation or the effect it would have on emissions is federally enforceable.”
In summary, PTE is the potential uncontrolled emission rate for a piece of equipment based on the maximum design capacity and unlimited operation of the equipment. PTE can be reduced by addressing physical limitations to the equipment operating at maximum capacity, using air pollution control equipment, restricting hours of operation, or restricting usage of fuel/raw materials. These limitations must be federally and practically enforceable in order to be considered in the PTE.
Almost all emissions calculations can be reduced to throughput multiplied by an emission factor. For sources with emissions capture and control devices, emissions calculations can be reduced to the following equation: [Throughput]x[Emission Factor]x[Capture Efficiency]x[1-Control Efficiency]+[Throughput]x[Emission Factor]x[1-Capture Efficiency]. 
For a visual representation of this calculation process, the below graphic illustrates the high-level emissions components for a generic process: 

As a straightforward example, the PTE of a boiler would be the calculated emissions from the boiler if it were fed the maximum amount of fuel for every hour of the year. If this boiler were rated at 50 MMBtu per hour, and had an emission factor of 0.05 pounds of particulate matter (PM) per MMBtu of fuel, the PTE of PM would be calculated using the following: 
[50 MMBtu/hour]x[0.05 lb PM/MMBtu]x[8,760 hours/year]x[1 ton/2000 lb] = 10.95 tons PM per year.
By adding the PTE of all equipment on-site, you can determine the facility-wide PTE.

Why is Potential to Emit (PTE) Important?

Facility-wide PTE is the key to determining the source status of your facility for operating permit applicability. The applicability is based off the facility-wide PTE in comparison to the Part 70 major source thresholds of 100 tons per year for criteria pollutants, 25 tons per year for combined hazardous air pollutants (HAPs), and 10 tons per year for any individual HAP. In Kansas, there are three source tiers with respect to operating permits. The first and lowest source tier are true minor sources, or facilities with an uncontrolled facility-wide PTE below major source thresholds. These sources do not require an operating permit. Above that are synthetic minor or Class II sources. These facilities have a facility-wide PTE above the major source thresholds but take federally enforceable limits to keep actual emissions below the major source thresholds via a Class II operating permit. The final and highest source tier are major sources, or facilities with facility-wide PTE above major source thresholds. Major sources are required to obtain a Title V operating permit. 
Anytime equipment is added, modified, or removed from a facility, the facility-wide PTE is affected. These changes must be incorporated into the facility-wide PTE in order to confirm the current source status. If your facility-wide PTE is not kept up to date, you could find your facility is over or under permitted as a result of past equipment changes.

Where do I start?

Calculating facility-wide PTE starts with compiling a complete inventory of equipment with air emissions on-site. Once you have a complete list, you can determine the maximum throughput of each piece of equipment and identify the appropriate emissions factors to use in calculations. Other considerations such as control equipment used, enforceable limitations, etc. are typically addressed after the list of equipment and throughputs are generated. 
Determining facility-wide PTE can be a complicated process, as it requires a complete and accurate inventory of all emissions sources on-site. In addition, particulars like process bottlenecks, permit limitations, and equipment specifications can all add complexity to calculations. Additionally, in some instances, multiple sources of emissions factors must be considered (e.g. manufacturer specifications versus EPA default factors), which can bring additional nuance in determining which factors are most applicable to your equipment. 
Since most permitting projects require a speedy turnaround and to prevent potential permitting delays, it is paramount to ensure that facility-wide PTE is compiled and accurate prior to beginning your next project. 
If you have any questions about setting up facility-wide PTE calculations, or would like additional assistance, please contact Kristen Chrislip or Josh Garlock in Trinity’s Kansas City office.