The EPA reports that the estimated six nitric acid plants that will be built in the next 5 years will be subject to the Agency’s revised New Source Performance Standards (NSPS) for that source category. The nitric acid production NSPS has not seen a significant change since they were first promulgated in 1971. Most nitric acid is used to produce fertilizer. The EPA developed the amendments under a settlement with environmental groups that had threatened to sue the Agency for failure to review the NSPS for nitric acid production. There are an estimated 40 nitric acid plants in the United States.

Revised NOx limit

The main change to the NSPS is a reduction of the maximum NOx emissions limit from 3.0 pounds of NOx per ton of nitric acid produced (lb NOx/ton acid) to 0.50 lb NOx/ton acid. The limit is calculated as a 30-operating-day emissions rate for each operating day based on the previous 30 operating days. For periods during which there is little or no acid production (e.g., start-up or shutdown), facilities must use the average hourly acid production rate determined from data collected over the previous 30 days of normal acid production.

The revised NSPS apply to all new nitric acid production units (NAPUs) for which construction commenced after October 14, 2011. Existing NAPUs that undergo reconstruction or modification, as those terms are defined by the EPA, after that date must also comply with the NSPS. According to the EPA, Clean Air Act (CAA) Section 111, which sets out the requirements for NSPS, states that the standards need not be based on technology. Thus, the EPA has introduced the term best system of emission reduction (BSER) to replace best demonstrated technology (BDT). The current action identifies BSER as selective catalytic reduction (SCR), which is being employed by several existing facilities to achieve emissions reductions under the new limit.

The standards also contain a new provision that data generated by required performance tests be submitted to the EPA with an electronic reporting tool (ERT) to the Agency’s WebFIRE database.

NSPS applies at all times

Consistent with a 2008 opinion by the U.S. Court of Appeals for the D.C. Circuit in Sierra Club v. EPA, the standards apply at all times. Accordingly, the Agency has factored start-up and shutdown periods into the new limit. The EPA believes that periods of start-up and shutdown consume only several hours per month for this source category. “We conclude that a 30-day emissions rate calculated based on 30 operating days will allow affected facilities to meet the 0.50 lb NOx/ton acid at all times, including periods of start-up and shutdown,” states the Agency.

The EPA has also determined that CAA Section 111 does not require that emissions that occur during periods of malfunction be factored into development of CAA Section 111 standards. In the event that a source fails to comply with the standards as a result of a malfunction, the Agency states that it would determine an “appropriate response” based on, among other things, the good-faith efforts of the source to minimize emissions during malfunction periods, including preventive and corrective actions as well as root cause analyses to ascertain and rectify violations.

In addition, in response to an Agency action to enforce the standards, a regulated entity may assert an affirmative defense to a claim for civil penalties for violations caused by malfunction. The affirmative defense provision is intended to ensure adequate compliance while simultaneously recognizing that despite the most diligent efforts, emissions limits may be exceeded under circumstances beyond the control of the source. The affirmative defense is not available for claims for injunctive relief.

The amended NSPS for nitric acid production was published in the August 14, 2012, FR.