On April 29, 2010, EPA proposed the long-awaited IB-MACT Rules for both major and minor sources of hazardous air pollutants (HAPs). In parallel, EPA also proposed the New Source Performance Standards (NSPS) for Commercial and Industrial Solid Waste Incineration Units (CISWI) and the revised CISWI Definitions Rule. These recent rulemaking developments will have significant implications for many industries (including electric utilities) particularly those with biomass-fired sources.

The proposed IB-MACT Rule includes eleven (11) subcategories for new and existing units based on fuel type and boiler design.  Nine of these subcategories include emissions limits for PM (not including condensables), mercury (Hg), hydrogen chloride (HCl), carbon monoxide (CO), and dioxin/furans (D/F) and two of the subcategories include work practice standards. Work practice standards are included for existing units with heat input capacity < 10 mmBtu/hr and new/existing units firing > 90% natural gas or refinery gas or "Metal Process Furnaces". Emissions limits are included for new and existing units for the following subcategories:  

• Coal: Stoker, Fluidized Bed, and Pulverized Coal

• Biomass: Stoker, Fluidized Bed, Suspension Burner/Dutch oven, Fuel Cell)

• Gas (includes all gases except for natural gas and refinery gas)

• Liquid

As expected, the proposed emissions limits for PM, Hg, and HCl are significantly lower than the vacated rule. While the rule does allow for a fuel-based compliance option, it is unlikely that most sources will meet the proposed limits based on fuel analysis. In fact, many sources will need to install additional controls. In addition, the new rule does not include a risk-based assessment option for HCl and manganese (e.g., “Health Based Compliance Alterative”) that would have allowed many sources to comply with the emissions standards for total selected metals (TSM) and HCl under the vacated rule.

Of note, 40 CFR Part 63.7525 (the IB-MACT Rule) requires the installation of a CO/O2 continuous emission monitoring system (CEMS) for boilers and process heaters with a heat input capacity greater than or equal to 100 mmBtu/hr. Additionally, boilers and process heaters with a heat input capacity greater than or equal to 250 mmBtu/hr that combust coal, biomass or residual oil are required to install a PM CEMS.

The rules are expected to be published in the Federal Register within the next few days. EPA is proposing a 45-day comment period for all rules, which begins on the date of publication in the Federal Register. Copies of the proposed rules are available in our FTP library. Additional information can be found on EPA’s website: http://www.epa.gov/airquality/combustion/actions.html. Also, we will post more information on our website regarding these rules as it becomes available. Please contact Rob Barton at 919-791-3129 for more information.