In response to reconsideration requests from industry, the EPA has proposed changes to two sets of air standards affecting new power plants–the mercury air toxics standard (MATS) and New Source Performance Standards for power plants (Utility NSPS). Both standards were issued in February 2012. 

According to the Agency, the proposed amendments will still require that affected new units use the same types of state-of-the-art control technologies to meet the revised emissions limits as they would have used in the previously finalized standards.  Standards for existing units would not be affected by the proposed revisions.

Data shortfall

Following promulgation of the standards, the EPA received 24 petitions to reconsider the standards.  The petitioners asserted that the Agency did not use all the data in the record for the best performing sources in establishing certain final new source emissions limits for coal- and oil-fired electric utility steam generating units (EGU).  Specifically, industry claimed that EPA’s emissions-setting rules did not consider necessary data regarding filterable particulate matter (PM) and hydrogen chloride (HCl) applicable to new coal-fired EGUs and filterable PM applicable to new solid oil-derived fuel-fired EGUs.  The EPA agreed with the petitioners.  In general, the proposed changes result in emissions limits that are slightly less stringent.

The EPA also identified a few additional new source limits for which the Agency did not use all data in the record when setting the standards in the final rule.  As a result, the action includes proposed revisions to the sulfur dioxide limit applicable to solid oil-derived fuel-fired EGUs, the filterable PM limit applicable to continental liquid oil-fired EGUs, and the lead and selenium limits applicable to coal-fired EGUs based on consideration of all the data in the record from the best performing sources for the pollutants at issue.

Start-up and shutdown

Also in response to the petitions, the EPA is proposing to revise and clarify requirements that apply during periods of start-up and shutdown in the MATS and start-up and shutdown for PM in the Utility NSPS.  In addition, the proposal includes a definition of start-up and shutdown to accommodate operation of cogeneration units and to reflect start-up conditions for all affected units, particularly supercritical units.

Because EPA expects that the types of pollution control equipment companies planned to install in new EGUs will not be affected by the relatively minor amendments proposed, the Agency asserts that there will also be little change in the resulting emissions, use of energy, compliance costs, and monetized benefits. 

It is also unlikely that the proposed changes would cause the regulated sector to withdraw legal challenges to the MATS.  A federal appeals court has held suits against the EPA and the MATS in abeyance while the Agency completes its reconsideration of the standards.

Click here to read EPA’s proposal to amend the MATS and Utility NSPS.