EPA Proposes Slightly Modified MATS for New Power Plants

A reconsidered proposal issued by the U.S. Environmental Protection Agency (EPA) on Friday sets out slightly weakened emission limits for mercury, particulate matter (PM), acid gases, and certain individual metals for future coal- and oil-fired power plants.

The proposal was based on "new information and analysis that became available to the agency" after the Mercury and Air Toxics Standards (MATS) and Utility New Source Performance Standards (NSPS) were finalized on Dec. 16, 2011. Following publication of the rule in the Federal Register on Feb. 16, 2012, the EPA received 20 petitions for reconsideration of the MATS and four for reconsideration of the Utility NSPS. On July 20, the agency announced it would grant reconsideration of certain new source issues.

As POWERnews reported in July, petitioners raised concerns associated with measurement issues related to mercury and the data set to which the variability calculation was applied when establishing the new source standards for PM and hydrochloric acid (HCl). The EPA on Friday said the reconsideration was also based on assertions by petitioners that the agency did not base the sulfur dioxide (SO2) standard on a regulated utility unit and had finalized startup and shutdown provisions before the public had a chance to review and comment on them.

Friday’s proposal does not change final emission limits for existing power plants, and it will still require new power plants to use the same control technologies to meet standards as the previously finalized standards. Changes to new source emission limits for filterable PM and HCl apply to new coal-fired generating units, and changes for filterable PM apply to new solid oil-derived fuel-fired generating units.

The proposal also seeks to revise the SO2 limit for solid oil-derived fuel-fired generating units, the filterable PM limit applicable to continental liquid oil-fired generating units, and the lead and selenium limits applicable to coal-fired generating units. Meanwhile, the EPA said it was seeking comments for possible revisions to the mercury limit applicable to low-rank virgin coal-fired generating units.

"The proposed updates are calculated from data about the emissions rates achieved by the best performing source for each of the air toxics or surrogates. The calculated limits remain very low and will still require new power plants to be among the most modern and cleanest ever built," the agency said.

The Nov. 16 reconsideration also proposes to revise and clarify requirements that apply during periods of startup and shutdown in MATS and startup and shutdown for PM in the Utility NSPS, as well as other minor technical corrections.

The rule is expected to be finalized in March 2013, following a 30-day comment period after publication in the Federal Register. No significant changes in cost, emission reductions, or health benefits are expected from the reconsideration, the EPA said.

Several power companies looking to build new coal facilities—including White Stallion Energy Center, Sunflower Electric Power Corp., Tri-State Generation and Transmission Association, Power4Georgians, Deseret Power Electric Cooperative, and Tenaska Trailblazer Partners—had asked U.S. Court of Appeals for the District of Columbia Circuit to force the agency to set a deadline by which it must finalize a rule reconsidering MATS for new power plants.

Industry experts said they were still reviewing the rule, though none was convinced the changes would increase a utility’s ability to build a new coal plant. Clean air groups lamented the changes as a "moderate weakening of the emissions limits for new plants.”

With the election over, the proposed rule is the first of several expected from the EPA in the coming months. EPA’s assistant administrator for air and radiation, Gina McCarthy, last week told attendees at a meeting of the Ozone Transport Commission and Mid-Atlantic/Northwest Visibility Union that the agency was on track to finalize reconsidered air toxics emissions standards for boilers within the next few months. Meanwhile, McCarthy last Wednesday told the National Association of Regulatory Utility Commissioners that rules regulating greenhouse gas emissions from existing power plants were "years away." A greenhouse gas NSPS for new fossil fuel–fired power plants proposed in April garnered nearly two million comments.

Sources: POWERnews, EPA

—Sonal Patel, Senior Writer (@POWERmagazine)

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