Mercury and Air Toxics Standard
(previously known as HAPs Rule or Utility MACT Rule)
Highlights:
- Issued: Signed Dec. 16th, 2011; publication in Federal Register expected mid-January 2012; becomes effective 60 days after publication
- Compliance: Three years from the date final rules become effective with two, one-year extension possibilities
On Dec. 16, 2011, the U.S. Environmental Protection Agency (EPA) signed a final rule to reduce emissions of mercury and air toxics from new and existing coal and oil-fired electric utility steam generating units.
What - The rule addresses emissions of mercury and air toxics, including metals, acid gases, organics and dioxin/furans. The rule replaces the Clean Air Mercury Rule, vacated by the D.C. Circuit Court in 2008.
What is MACT?
Maximum Available Control Technology (MACT) is a performance-based approach for setting emissions standards for certain pollutants. When developing a MACT standard for a particular source category, EPA looks at the level of emissions currently achieved by the best-performing similar sources. These emissions levels set a baseline (the "MACT floor") for the new standard.
The rule sets numeric limits for hydrogen chloride (a surrogate for acid gases), filterable particulate matter (surrogate for non-mercury metals) and mercury. The limits are based on the emissions being achieved by the average of today's top 12 percent best - performing similar sources (MACT).
How - Compliance with the MATS could result in very specific control equipment for many plants. EPA identifies specific technologies - wet and dry flue gas desulfurization (FGD or scrubber) systems, dry sorbent injection, activated carbon injection and fabric filters - as proven and available technologies to reduce emissions of mercury and air toxics.
Who - According to EPA, this rule affects about 46 percent of the nation's electricity generation: 1,350 coal- and oil-fired units at 525 power plants. Natural gas generating units are not included.
When - Plants must comply three years from the date the rule goes into effect, or approximately March 2015. Permitting agencies (typically state agencies) could grant an Administrative one-year extension for units requiring major retrofit or replacement projects. An additional one year Enforcement order extension may be available to units identified as "critical for reliability purposes." The criteria and procedures for obtaining these extensions remain unclear.
At the same time, EPA has proposed or finalized other rules that will significantly impact coal-fired electricity generators and their customers:
At the same time, EPA has proposed or finalized other rules that will significantly impact coal-fired electricity generators and their customers:
