Emissions Control

The Maximum Achievable Control Technology, or MACT, regulation now in development under the 1990 Clean Air Act Amendments will place strict and expensive emission controls on many wood products plants. Mills most likely to be affected are those already most regulated-OSB and MDF facilities. Some softwood plywood and particleboard facilities also will be affected, although it is unclear at this time how many.

For some plants, the cost of implementing MACT requirements could run more than $1 million in capital investment and $1 million in annual operating costs.

Background
The Clean Air Act Amendments required the Environmental Protection Agency (EPA) to develop regulations to reduce emissions of "hazardous air pollutants" from industrial facilities. Congress specifically listed 189 compounds as hazardous air pollutants, including methanol, formaldehyde, phenol, and MDI. EPA also was to identify industrial source categories for which these regulations would be developed.

One of the source categories identified by EPA was plywood, particleboard and other composite wood products plants. (EPA now officially refers to this category as "plywood and composite wood products manufacturing," which covers softwood and hardwood plywood, particleboard, OSB, MDF, hardboard, fiberboard, glulam timber, laminated veneer lumber, wood I-joists, laminated strand lumber and parallel strand lumber.) Standards for wood products plants were to be promulgated by November 15, 2000. However, EPA recently acknowledged it will likely miss that target date by at least one year.

EPA has indicated it expects the MACT emission standards to apply only to mills designated as "major sources" of hazardous air pollutant emissions. A major source is defined as a facility that has the potential to emit 10 tons per year (tpy) of any one "hazardous air pollutant" or 25 tpy of two or more hazardous air pollutants. Facilities emitting less than these amounts are defined as "area sources" and will likely not be affected by the standards.

MACT standards for existing plants must reflect emissions being achieved by the "best performing" 12 percent of the plants. If 12 percent or more of a category of facilities have installed a particular piece of control equipment which reduces emissions of hazardous air pollutants, the average reduction efficiency of that technology will be used to set the emission limits for major sources in that category.

As an example, 63 percent of all US OSB dryers are controlled by regenerative thermal oxidizers (RTO), so this type of control equipment will probably form the basis of the required reduction efficiency for all OSB dryers. Reduction efficiency is the ratio of consumed emissions to uncontrolled emissions, expressed as a percent.

Although these controls were originally installed to reduce emissions of volatile organic compounds (VOCs), they also reduce emissions of organic compounds that are listed as hazardous air pollutants (e.g., formaldehyde), and thus EPA will consider them for MACT purposes. New facilities may be treated the same way, or may be forced to apply the single best-performing technology.

Data Collection Efforts
Determined to have the MACT regulations based on accurate data and reliable emission test results, the panel industry undertook a major field study in 1997 to quantify emissions of hazardous air pollutants. The study was funded through the American Forest & Paper Association (AF&PA) and conducted by the National Council for Air and Stream Improvement, Inc. (NCASI).

Twenty-nine representative facilities were sampled, with the primary focus on emissions from presses and dryers. In summary, the results showed that MDF, OSB, particleboard, and hardboard plants are typically major sources; that softwood plywood mills may be major sources, and that hardwood plywood and LVL mills are not typically major sources. Methanol and formaldehyde were found to be the major compounds emitted from wood drying and pressing operations. The study results were published in a series of NCASI technical bulletins during the last half of 1999.

EPA conducted its own information collection effort in late 1998. The agency's consultant, Midwest Research Institute (MRI), last year organized and analyzed responses to this survey, which includes equipment descriptions, production levels, raw material usage, air flows and emissions data. In addition, industry representatives hosted several mill tours for EPA and MRI staff in 1998 for the purpose of improving EPA's understanding of the wood products industry, including the difference in manufacturing techniques among various product types. EPA released its survey database to association representatives in mid-November so that industry would have an opportunity for independent review.

Current Activity
The industry has advanced the idea of subcategorizing mills along traditional product lines because different manufacturing processes result in varying emission levels. EPA has begun to meet with industry representatives to clarify how much subcategorization is desired, and to discuss the justification for the proposed subcategories. At a meeting in mid-November, association representatives presented preliminary proposals for subcategories. APA-The Engineered Wood Association represented OSB, softwood plywood and engineered wood product facilities; the Composite Panel Association represented particleboard and MDF manufacturers; and the American Hardboard Association represented hardboard and fiberboard manufacturers.

It was emphasized at that meeting that the MACT regulation should permit flexibility in the application of control technologies from two standpoints. First, the need for pre-filters or pre-controls prior to incineration devices (e.g., an RTO) should be determined on a mill-by-mill basis. Second, mills should be allowed to utilize innovative technologies as they become available, provided the emission reduction efficiency closely resembles the floor technology.

The second point is important because mills will have three years to meet the MACT requirements once EPA issues the final regulation. With EPA's present schedule, this implies a final compliance date in late 2004. Thus, innovations over the next two to four years could substantially change the available pollution abatement options.

EPA also was invited to review a life-cycle evaluation of incineration technology sponsored by the industry. Incineration (RTO and regenerative catalytic oxidation, or RCO) controls have typically been criticized by the industry for a number of reasons, including: 1) they were originally developed for high-concentration exhaust streams, 2) they use a lot of natural gas and generate a lot of heat, 3) they actually cause a net increase in nitrous oxides, a contributor to ozone formation, 4) natural gas losses during transportation could cause global climate concerns, 5) problems with maintenance and stable emission reduction efficiency, and 6) the combination of these effects may not result in a net environmental benefit.

The industry-sponsored analysis proposes to study these factors and to compare the overall benefits of other abatement technologies. One possible outcome might be to identify a technology that has a reduction efficiency slightly lower than that for incineration, but because of improved life-cycle maintainability and fewer environmental offsets, might be viewed favorably compared with incineration. EPA staff expressed interest in reviewing the industry's progress on this issue.

One of the two major hazardous pollutants emitted from wood drying and pressing is methanol. EPA is currently reviewing a petition submitted by AF&PA to remove that chemical from the list of hazardous air pollutants. If this should occur, it would be very good news indeed for certain product classes, including softwood plywood, because methanol emissions can be more than 10 tons from a softwood plywood mill, depending on size and other factors.

If methanol were to be de-listed, most softwood plywood mills would be considered area sources, rather than major sources of hazardous air pollutants, and thus would likely not be affected by the standards. An initial EPA decision on the petition is expected in August, 2000.

Kurt Bigbee is Quality Services Division project coordinator at APA-The Engineered Wood Association. He serves in that capacity as APA's liaison representative to industry environmental affairs activities. John Pinkerton, vice president, air quality at the National Council for Air and Stream Improvement, Inc., provided technical review of this article.

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