Understanding Further Revised US EPA Boiler Standards

By Glenn Unterberger and Michael Duffy | January 25, 2012

The emission standards for industrial, commercial and institutional boilers are back on the front burner at the U.S. EPA. In May, the agency suspended the standards it had promulgated just two months before, over concerns that compliance might be too costly or even unachievable. Now the EPA has published proposed revisions to the hazardous air pollutant emission standards for certain boilers and incinerators, including biomass-fueled boilers. The EPA projects the proposed changes, published Dec. 23, will cut the cost of implementation nearly in half from the original proposed rule, while still meeting the requirements of the Clean Air Act.

Several new subcategories of units are proposed that may allow for more precisely tailored and, for some pollutants, less stringent emission limits for certain biomass units. The first is for boilers designed to combust kiln-dried wood, with new emission limits for particulate matter (PM) and carbon monoxide (CO) proposed for this subcategory. Second, separate numeric emission limits are proposed for PM and CO for the hybrid suspension/grate boiler subcategory (previously not assigned separate limits as a combustion-based fuel subcategory). Third, dutch ovens and suspension burners are proposed as two separate categories, based on their inherently different design, with each having separate emission limits for PM and CO. The EPA requests comment on whether further subcategorization of biomass units is appropriate.

The EPA also proposes revision of certain emission standards in light of new data. Most importantly, a review of test data EPA had relied upon for dioxin/furans for all subcategories led the agency to determine that the test emissions were too low to be measured accurately. It now proposes a work practice standard for dioxin/furan emissions, requiring an annual tune-up in lieu of numeric emission limits.

Also under the most recent proposed revisions, the PM continuous emission monitoring system (CEMS) requirement would be eliminated for biomass units. The EPA expressed doubts that this technology will have the ability to accommodate the unpredictable variety of biomass fuel constituents and moisture content, noting that it has not been sufficiently demonstrated in practice and relies on a single calibration point to measure emissions from a specific fuel type. The agency noted it would be impractical to replicate, during performance testing, all of the varying fuel conditions necessary for calibrating the monitor. Since PM CEMS cannot be applied with the accuracy necessary for compliance assessment, the EPA proposes continuous monitoring of operating parameters to determine compliance, which will substantially reduce monitoring costs.

The proposal also clarifies the accompanying Non-Hazardous Secondary Materials rule, which sets guidelines for determining which materials are “solid waste,” and therefore subject to the more stringent emission limits of the Commercial and Industrial Solid Waste Incineration rule. EPA clarifies that certain biomass materials are considered traditional nonwaste fuel under the NHSM rule, and therefore not subject to the CISWI rule. Further, the proposal lists specific biomass materials to be included within the definition of “clean cellulosic biomass,” thus allowing them to be treated as traditional fuel. Additionally, the proposal lists several NHSMs as nonwaste when burned as a fuel in a combustion unit for which EPA has sufficient information to determine that discard is not occurring. This includes certain NHSMs which, though not meeting the criteria for “legitimate” fuel in all instances, would be considered a nonwaste fuel after balancing the legitimacy criteria with other relevant factors. Resinated wood, for example, would be deemed “not a solid waste material when used as a fuel regardless of whether it remained within the control of the generator.”

The EPA promulgated the March regulations under a court-imposed deadline, and when the agency suspended the regulations to consider revisions, another suit was brought to vacate that “stay.” On Jan. 9, the D.C. District Court vacated the stay. Assuming the EPA holds to its announced schedule to promulgate final revisions by April, it is now uncertain whether existing sources will be required to comply with these new rules by 2014 according to the reinstated regulations, or by 2015 according to the proposed revisions. Further litigation may ensue, even as the EPA proceeds to finalize the revisions and implement the rules. How such litigation will affect the rules’ implementation remains to be seen.

The EPA must receive public comments on the proposed revisions by Feb. 21.

Authors: Glenn Unterberger
Partner, Ballard Spahr LLP
(215) 864-8210
Michael Duffy
Associate, Ballard Spahr LLP
(215) 864-8248