US2000 12241175.2 September 8, 2011

The Honorable Lisa P. Jackson

Administrator U.S. Environmental Protection Agency Ariel Rios Building 1200 Pennsylvania Avenue, N. W.

Mail Code: 1101A Washington, DC 20460

Re: Supplement to Petition for Reconsideration and Amendment of the Major Source Boiler MACT Rule; EPA Docket ID No. EPA-HQ-O AR-2002-0058

Dear Administrator Jackson:

On behalf of the American Home Furnishings Allianc e (AHFA), I am submitting this written supplement to AHFA’s Petition for Reco nsideration and Amendment of the Major Source Boiler MACT Rule (the Petition). Our original Petition was filed on May 20, 2011. In our Petition, we identified several c oncerns with the Major Source Boiler MACT Rule. In particular, we urged EPA to (a) esta blish a subcategory for boilers combusting wood fuel with low moisture content and (b) establish appropriate emission limits and work practice standards for suc h boilers. In this supplement, we provide further information to justify the creation of a new subcategory for boilers that combust fuel that we describe as Dry Wood Fuel (DWF).

Section 112(d)(1) of the Clean Air Act authorizes EPA to distinguish among “classes, types, and sizes” of sources that are sub ject to MACT standards. We believe that boilers that combust DWF are distinguishable f rom other boiler in the various subcategories in the Major Source Boiler Rule. For the reasons set forth below, we recommend that EPA establish a new subcategory enti tled “Nondrying Suspension

Boilers.”

Dry Wood Fuel Characteristics

For purposes of this analysis, we define DWF as wo od with a moisture content less than or equal to 20%. The average moisture co ntent of DWF is approximately 0.5% - 1.5%, based on fuels test results collected for the original Boiler MACT. Examples of DWF include (but are not limited to):

• Dry lumber, wood veneers, and other similar wood pr oducts; and

• Dry wood products (containing resin adhesives) deri ved from primary and secondary wood products manufacturing and compr ised of such items as board trim, sander dust, and panel trim. 3 1 7 W . H i g h A v e . , 1 0 t h F l o o r

P . O . B o x H P - 7

H i g h P o i n t , N C 2 7 2 6 1

P h o n e 3 3 6 . 8 8 4 . 5 0 0 0

F a x 3 3 6 - 8 8 4 - 5 3 0 3Lisa P. Jackson September 8, 2011 Page 2

US2000 12241175.2 DWF is a clean cellulosic material that is composed principally of carbon, hydrogen, and oxygen. It has distinctively low ash content a t less than 1 percent mineral ash, and is very low in heavy metals. The chlorine and sulf ur content of DWF is low compared

to coal.

DWF as produced and combusted has low moisture con tent. Indeed, DWF is much drier than other biomass fuels, which have moi sture contents that may range from 25% to 70%. Because DWF is produced as dry bi omass, driving off moisture in the combustion chamber consumes very little energy when compared to other biomass fuels. As a result, the heating value for DWF as received is on average higher than other biomass fuels. The range of DWF heating values is approximately 7,800 – 9,000 BTU/lb with an average typically near 8,100 B TU/lb. 1 Published heating values for other biomass fuels range are in the range of 6 ,450-8,200 BTU/lb.

Unlike many other fuels combusted in boilers, DWF is a renewable fuel. DWF produces no net greenhouse gas (GHG) emissions when combusted. Recognizing that wood and other forms of biomass may be considered c arbon-neutral fuels, EPA has instituted a three-year deferral of PSD permitting requirements for biogenic CO2 emissions, and the IPCC has provided statements sup porting the concept of carbon neutrality for biogenic fuels. If combustion of DW F became impracticable under the Boiler MACT rule, DWF would be disposed of in landf ills where it would likely lead to methane formation through anaerobic decomposition. Any reduction in DWF combustion would likely be replaced by combustion o f fossil fuels.

Characteristics of Dry Wood Fuel Boilers

DWF boilers are designed to accommodate the unique characteristics of DWF, which must be handled and combusted differently tha n other biomass fuels. Because DWF is a unique fuel with its own combustion profil e and emissions characteristics, boilers must be configured and operated to ensure e fficient DWF combustion. In addition, DWF boilers are designed to accommodate h ighly variable conditions and swings in operations.

In particular, DWF boilers are unique because more of the combustion occurs in suspension when compared with other boilers iden tified the Boiler MACT Rule, such as a standard suspension boiler or a hybrid suspens ion grate boiler. Therefore, we believe that an appropriate name for subcategorizin g DWF boilers is “nondrying suspension boilers.” Based on our survey of our i ndustry boilers and their unique characteristics, we define nondrying suspension boi lers as: Boilers less than or equal to 70 MMBTU/hr (heat input capacity) that combust l ow moisture fuel while suspended in air and complete combustion of the fue l on grates or floors.

1 Based on fuels testing by AHFA members in 2010.Lisa P. Jackson September 8, 2011 Page 3

US2000 12241175.2 As a result of increased combustion of DWF in susp ension, nondrying suspension boilers have a significantly higher heat release rate than other biomass boilers combusting higher moisture fuels. Moreover , nondrying suspension boilers require much higher excess air rates than other boi lers. The high excess air promotes better turbulence, but reduces residence time in th e combustion zone. This combustion of dry fuel results in relatively high c ombustion temperatures in the boilers and high heat release rates. AHFA is worki ng with a boiler consultant to document the time, temperature, and turbulence prof ile for nondrying suspension boilers. We will provide that information to EPA a s soon as it is available.

The fuel storage and feed systems are integral to nondrying suspension boilers. Nondrying suspension boilers include dedi cated pneumatic fuel feed systems, preceded by dry fuel storage such as silos or cover ed sheds. Nondrying suspension boilers include a continuous DWF supply to the feed ers that are specifically designed to control the DWF feed rate. Pneumatic injection i s used to distribute the DWF throughout the width and depth of the boiler.

Since both suspension and grate (or floor) combust ion occur, the temperature profile within the boiler is highly variable. As a consequence, steam production and production of carbon monoxide (CO) vary significant ly over even short periods of time due to changing species and geometry of the DWF and the changing conditions within the boiler. Combustion in suspension and a high pe ak heat combustion temperature result in a unique emissions profile, especially wi th respect to CO, volatile HAP, and PM. For other key pollutants related to fuel type , combustion of DWF results in very low emissions of heavy metals, mercury, hydrogen ch loride (HCl), and sulfur dioxide (SO2).

PM Limits for the Nondrying Suspension Boiler Subca tegory

In the Major Source Boiler Rule, EPA classified no n-mercury metallic HAP as a fuel-dependent pollutant. EPA then identified PM a s a surrogate for non-mercury metallic HAP. Finally, EPA established a single PM limit that applies to all existing solid

fuel boilers. AHFA believes that PM emissions are primarily a function of boiler design and operation. Thus, the unique configuration of n ondrying suspension boilers

indicates that PM emissions should be evaluated for this unique subcategory, rather than grouping those boilers with the non-discrete s ubcategory consisting of all solid fuel boilers. We urge EPA to establish PM emission standards for the proposed nondrying suspension boiler subcategory.

Conclusion

Nondrying suspension boilers are unique devices by virtue of their design and operation as well as the fuel they combust. Placin g nondrying suspension boilers in a subcategory with other boilers with different desig n, operating, and emission characteristics would not be appropriate, and would result in unachievable MACTLisa P. Jackson September 8, 2011 Page 4

US2000 12241175.2 emission limits. Therefore, AHFA respectfully urges EPA to establish a separate subcategory for nondrying suspension boilers in the Major Source Boiler MACT Rule.

We welcome the opportunity to continue working wit h EPA during the reconsideration process. Please contact me at 336- 884-5000, extension 1017 or bperdue@ahfa.us if you have any questions about this supplemental filing. Thank you for your consideration of this important issue.

Sincerely,

Bill Perdue Vice President of Regulatory Affairs

cc (via electronic mail): Bob Wayland Brian Schrager Jim Eddinger