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July 24, 2012
MATS to be 'reconsidered'

Owners and operators of fossil-fuel-fired power plants and the various advocates of these utilities derived a small measure of hope from the EPA, which has responded to multiple petitions with a brief letter stating that it would reconsider several compliance aspects of its December 2011 mercury air toxics standard (MATS). The 1-page letter said the reconsideration would focus on standards for new sources but revealed little about precisely which parts of MATS the EPA is reconsidering. The Agency says it will soon issue a Federal Register notice describing the specific issues that will get a second look. Issuance of a final action based on the reconsideration is scheduled for March 2013.

1,100 units affected

MATS imposes numerical emissions limits on mercury, particulate matter (PM, a surrogate for toxic nonmercury metals), and hydrochloric acid (a surrogate for all toxic acid gases) from existing and new power plants burning coal and oil. Overall, about 90 percent of all potential mercury emissions would be prevented from release. Concurrent with publication of MATS, the EPA issued revised New Source Performance Standards (NSPS) for emissions of PM, SO2, and NOx.

The EPA estimates that about 1,100 coal-fired units and 300 oil-fired units at 60 power plants are affected by the actions. The EPA “expects that dozens of coal-fired plants already meet at least some part of the standards.” But about 40 percent of coal-fired plants still do not use advanced emissions controls, says the Agency. Compliance is required 3 years after the effective date, but state implementing agencies have the authority to extend that to 4 years.

Unrealistic time frame et al.

The list of industry objections to the rule is long and includes health benefits that are overstated by the EPA, costs that are underestimated, emissions standards that are technologically unachievable, unrealistic compliance deadlines, closure of power plants, threats to grid reliability, and loss of jobs.

Regarding technical issues, one petition from the Institute for Clean Air Companies (ICAC) argues that MATS’s mercury emissions limit for new units is so low (99.7 percent removal efficiency) that existing continuous emissions monitoring systems (CEMS) are not sophisticated enough to confidently measure compliance. The ICAC therefore recommends that the EPA raise the emissions limit to “address the real-world constraints of available monitoring equipment.”

'Proven monitoring methods'

In its letter, the EPA states that measurement issues related to mercury are among the items that will receive reconsideration. “Our expectation is that under the reconsideration rule, new sources will be required to install the latest and most effective pollution controls and will be able to monitor compliance with the new standards with proven monitoring methods,” states the EPA.

The Agency states that it is also reconsidering the “data set to which the variability calculation was applied when establishing the [NSPS] for particulate matter and hydrochloric acid.”

EPA’s response to the requests for reconsideration is at http://www.epa.gov/mats/pdfs/20120720letter.pdf.

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