MACT Madness

The U.S. EPA has released an overhauled final version of the Maximum Achievable Control Technology rules, and the biggest changes will affect biomass boilers.
By Lisa Gibson | March 22, 2011

When the proposed Maximum Achievable Control Technology rules were released last April, a flurry of worry and borderline disgust engulfed the biomass power industry―concerned that it would soon be spending millions of dollars to install emission controls for hazardous air pollutants in existing units. It seemed the U.S. EPA’s proposals would mean that, or shutting down. Similarly, some developers feared they would have to scrap their plans, as the proposal made them uneconomical and burdensome.

The nearly 5,000 comments submitted to the EPA during the public comment period pointed out what some believed to be flaw after flaw in the proposal. Biomass industry proponents worked to convince the agency that the rules were duds and did not reflect the realistic environment surrounding the biomass power industry, among others. Overwhelmed with the number of comments containing vital information, the EPA asked the U.S. District Court for the District of Columbia to grant it an extension of either six or 15 months past its Jan. 16 final rule deadline, to allow more time to review the comments and incorporate any needed changes. The latter was the preferred option, as it would accommodate a complete reproposal of the rules, along with another comment period. After a short, five-day extension for the court to mull over the request, it was denied and instead the EPA was granted only one month to craft the final rule, which it promised would differ significantly from the proposal.

So with the biomass power industry on the edge of its seat anxiously awaiting a rule that could potentially devastate development, the EPA released its final rules on Feb. 23, cautioning up front that they were completely rewritten and compliance would cost about $1.8 billion less than projections for the proposed rules, a reduction of about half.

“We received more than 4,800 comments that shed new light on a number of key issues,” says Gina McCarthy, assistant administrator for EPA's Office of Air and Radiation. “Based on this feedback, EPA revised the draft standards and found we could reduce emissions at a lower cost and still achieve the health benefits required under the law.” The rules are realistic, achievable and reasonable, she adds.
The EPA expected it would not be granted its extension, McCarthy discloses, and thus began overhauling the rule immediately, shifting away from simply massaging the original proposal to rewriting it completely. “So while we would have preferred to have done it in a different process, we’re pretty comfortable with the rule that’s gone out,” she says. “We think it’s well-thought-out.”

Boiler Breakdown

The actions released Feb. 23 encompass standards for four source categories—major source industrial, commercial and institutional boilers and process heaters; area source industrial, commercial and institutional boilers; commercial and industrial solid waste incinerators (CISWI); and sewage sludge incinerators—as well as an updated definition of solid waste, crucial in determining which rules a technology will fall under.

The biggest change to the final rules that will save the most money in comparison with the proposal comes in the section dedicated to boilers at major source polluter locations. Major sources are categorized by the release of more than 10 tons per year of any single air toxic or 25 tons per year of any combination of air toxics. Based on the data received in comments, the major source rule—divided into 15 subcategories of units burning natural gas, biomass, coal and other fuels—combines coal and biomass boilers into one solid fuel category. That closes the loophole for other solid fuel that may be burned, such as tires, and provides biomass boilers more flexibility. “As a result, the standards make it clear that many existing large biomass boilers no longer have to install scrubbers to control acid gases or lower mercury, because the data tells us that most of them don’t emit those pollutants to any great extent,” McCarthy says. The major source rule establishes emission standards for mercury (Hg), carbon monoxide (CO), dioxin/furans, hydrogen chloride (HCl), and particulate matter (PM).

The rolling together of the two categories means higher and more easily achieved emission limits for PM, HCl and Hg in all existing biomass units. It also results in higher emission limits for three existing subcategories of biomass boilers for dioxin/furans. For CO, however, emission limits were decreased in two subcategories of existing units. And for new biomass units, emission standards for mercury and dioxin/furans were increased in all subcategories, but PM and HCl standards were decreased. CO standards were increased for two biomass subcategories and decreased for two.

“By combining the coal and the biomass boiler categories for those three pollutants (PM, HCl and Hg), it has resulted in higher emission limits for the [existing] biomass units that will likely lead to them not having to install very expensive pollution control equipment that the original proposal would have required,” says Deanna Duram, managing consultant with Trinity Consultants, headquartered in Dallas. But while the improvements for existing biomass units are a positive, the decreased standards for PM and HCl in new units will be challenging, she adds.

Another important change also comes in the boiler categories. “We learned during the comment period that both new and existing small boilers are designed in a way that does not accommodate monitoring for specific pollutants,” McCarthy says. “That’s true whether you’re a major or area source.”

In light of that realization, the EPA created a subcategory for small boilers—classified by a heat input capacity of less than 10 million Btu per hour—requiring only tune-ups every two years, in lieu of compliance with numeric emission standards. Limited-use boilers are also only required to conduct the tune-ups as well as all existing area source biomass boilers, and new area source biomass boilers with heat input capacity of 10 MMBtu per hour or greater are only required to meet PM limits. “It makes sense because these units are not a big piece of the pie in terms of toxic emissions and if we get them tuned up, they run more efficiently, more cleanly; they save money for the facilities and they keep emissions as low as they can get,” McCarthy says.

Existing units falling under the boiler and process heater categories must comply with the rules by 2014, and new ones must comply upon start-up.

Incinerator Issues

Both CISWI and sewage sludge incinerator rules control the five pollutants addressed in the boiler rules, as well as lead, cadmium, sulfur dioxide and nitrogen oxides. A major point of contention with the proposed rules in the biomass industry was the definition of solid waste, key to determining which rules a technology will fall under and subsequently how much money it will cost to comply. The deadline for compliance with CISWI rules is three years after the EPA approves a state plan to implement the standards, or 2016, whichever is earlier.

Generally, to classify as a fuel instead of solid waste, a material must not be discarded initially; must remain in control of the generator; must be managed as a valuable commodity; have meaningful heating value and be burned in units that recover energy; and contain contaminants that are comparable to or lower than that of traditional fuel products. A petition process is also included for material that does not remain in control of the generator but has not been discarded and meets the legitimacy criteria above.

Perhaps one of the most meaningful changes in the final definition for the biomass industry is the classification of resinated wood residuals as a nonsolid waste whether combusted in or out of the generator’s control, provided it meets the legitimacy criteria. That means forest products companies selling their board trim, panel trim, sander dust and other materials can consider them fuel. “The benefit in this change is basically the rule as proposed said once it goes off-site, it’s a solid waste,” Duram explains, adding that the material has always been considered a valuable fuel in the forest products industry. “They still have to meet legitimacy criteria, but this was, for a lot of my clients, a very important change in the final rule.”

As in the proposed rule, materials such as forest residuals, ag biomass and other clean cellulosic resources still qualify as fuels, but are now given the title of “alternative” traditional fuels.
Had the biomass materials not qualified as fuels and instead solid waste, the operations burning them would be subject to stricter emission limits. As they are, the limits will require emission reductions at 85 of the 88 currently operating CISWI, according to the EPA. The rule requires stack testing, monitoring, and additional monitoring for new sources. Annual inspections of emission control devices are also required, as well as annual visible emissions tests of ash handling operations, and owners and operators must follow certain procedures for test data submittal.

The sewage sludge incinerator rule includes multiple hearth and fluidized bed technologies and may require control device installations at about 196 of the 218 existing units, according to the EPA. The rules require provisions for testing, monitoring, recordkeeping, reporting and operator training. They were not included in the April 2010 MACT draft.

For more information on the rules, visit

Moving Forward

As a result of the significant changes in the final rules, the EPA announced a 60-day reconsideration period for certain aspects of the boiler and process heater portions, as well as for CISWI. The process will essentially replace the public comment period that would have been allowed with a 15-month extension.

Under the Clean Air Act, the EPA is obligated to regulate hazardous air pollutants from these sources and initially finalized a rule in 2004. It was vacated by the court in 2007, however, on the grounds that it did not properly distinguish “industrial boilers” from “solid waste incinerators,” which must be regulated separately, as per the CAA. The relevant definition of solid waste is not in the CAA, but rather the Resource Conservation and Recovery Act. The EPA, however, was tasked to determine which nonhazardous secondary materials are, and are not, solid waste as it relates to the CAA and MACT rules.    

The EPA fully expects petitions during the reconsideration period, McCarthy says, and promises to assess them fully, making further changes to the rules if necessary. “The rules we finalized [Feb. 23] are based on best scientific data,” she says. “They will lead to significant achievable reduction. They’ll promote tremendous public health benefits, and as we move forward with the next steps in the reconsideration process, we’ll make sure that these standards remain practical to implement and that American families can see the health benefits as soon as possible.”

McCarthy also promised that the EPA will work with the U.S. departments of agriculture and energy to make compliance as easy and as inexpensive as possible for effected operations. The rules do, she adds, encourage the use of cleaner technologies by the dirtiest polluters: coal-fired boilers. “I think the final rule does provide some good incentives for coal to look at cofiring with biomass as part of a less-expensive compliance strategy.”

Bob Cleaves, president and CEO of the Biomass Power Association, acknowledges the final rule is a large improvement, especially in the elimination of numeric emission standards for certain small biomass boilers, but doesn’t include the sweeping changes the BPA had hoped for. “Despite the best efforts by the administration and EPA, what we are left with is a rule that, in spirit, is a very positive development,” he says. “I think a number of important changes were made, but I think it remains problematic.” The solid waste definition continues to worry the biomass power industry, as it can still include materials such as urban wood waste in California. “We are not incinerators,” Cleaves emphasizes. During the reconsideration process, the BPA plans to petition for a facility-by-facility basis for the rule, rather than the current pollutant-by-pollutant structure.

While the new solid fuel subcategory of the major source rule increases some pollutant limits, the biomass power industry is still concerned about meeting the limits for mercury and dioxins, Cleaves says. He adds, though, that the subcategory does ease concerns considerably, and McCarthy agrees. “The move to solid fuel category really provided flexibility for some of the biomass units and I think it was appropriate because it allowed them to target their controls to the actual emissions that they most contribute,” she says.

Although Cleaves still has some complaints about the final rules, he is appreciative of the fact that the EPA attempted to better understand the biomass power industry and how those rules would affect it. “There’s no question that the EPA had a substantial learning curve in the past 12 months,” he says.

Author: Lisa Gibson
Associate Editor, Biomass Power & Thermal
 (701) 738-4952