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Environmental Protection
Determining maximum capacity and ensuring that permit limits are federally enforceable are critical to calculating PTE.
A facility may need to calculate its potential to emit (PTE) for various reasons. For a new plant or piece of equipment, potential-air-emission calculations are critical in determining which construction permitting program the project qualifies for. For existing facilities, these calculations are used to determine whether emission limits are needed in order for the facility to remain below particular operating permit thresholds.
The current definition of PTE, given in 40 CFR Section 52.21(b)(4), is: "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 the emissions is federally enforceable ..."
While it may seem straightforward at first glance, calculating PTE can be a confusing, timeconsuming and frustrating endeavor. Many existing units are grandfathered, meaning that they were built before state permitting programs were established, and thus they have no permit limits. The maximum capacity of these units is often difficult to determine. Many units were permitted with emission limits on one pollutant but not on others. Some units can be used for a variety of purposes, and other units can handle a wide variety of raw materials. These and other issues can make PTE calculation confusing.
Guidance for calculating PTE can be found in many places, including U.S. Environmental Protection Agency (EPA) memos, the New Source Review Workshop Manual (1), and previous state and EPA determinations. This article discusses each part of the definition of PTE, reviews the available guidance, and offers tips for avoiding potential pitfalls when calculating PTE.
Maximum capacity under the plant's physical and operational design
Potential emissions can loosely be defined as the amount of pollutant a source can emit when it runs at maximum production capacity, or the maximum pollution a source can generate.
In a court case involving Louisiana-Pacific Corp., the judge...