On June 4, 2010, U.S. EPA released its much anticipated proposed standards for industrial boilers to reduce hazardous air pollutants ("HAPs").   Since their release, EPA has faced an outcry that the proposed standards are "fundamentally flawed" or "unachievable."

So what is the controversy?

EPA’s boiler standards are supposed to reflect the application of the maximum achievable control technology (“MACT”). 

What is MACT?

MACT requires the maximum reduction of hazardous emissions, taking cost and feasibility into account.  The MACT must not be less than the average emission level achieved by controls on the best performing 12 percent of existing sources, by category of industrial and utility sources.

I highlighted a couple key terms in U.S. EPA’s definition. 

Cost and Feasibility-  Unlike other EPA standards, cost and feasibility in achieving the standards are relevant.  Many argue cost of compliance with proposed standards will be dramatically too high.

Best Performing 12%-  As discussed below, many assert EPA’s methodology for developing the top 12% performing sources is fundamentally flawed.  They assert EPA simply "cherry picked" certain sources and unfairly based its limits on too small of a data pool.

Controversy Builds

On August 2nd, 100 members of Congress submitted a letter to Administrator Jackson asking EPA reconsider its proposed boiler MACT standards:

EPA should use a method to set emission standards that is based on what real world best performing units can achieve.  EPA should not ignore biases in its emissions database, the practical capabilities of controls or the variability in operations, fuels and testing performance across many regulated sectors.

Impact on Biomass Industry

One group strongly opposing EPA is proposal is the biomass industry which believes the proposal unfairly lumps biomass in with all other fuels.  The biomass industry has indicated the standards, if finalized, could prevent the development of additional biomass sources.  The National Alliance of Forest Owners (NAFO) provides the following description of EPA’s flawed MACT methodology:

EPA explains that “[f]or each pollutant, we calculated the MACT floor for a subcategory of sources by ranking all the available emissions data from units within the subcategory from lowest emissions to highest emissions, and then taking the numerical average of the test results from the best performing (lowest emitting) 12 percent of sources.” 75 Fed. Reg. at 32019.This “pollutant-by-pollutant ” approach to determining MACT is not appropriate because it results in standards that do not reflect the performance of the best performing boilers for any fuel source. 

The CAA requires that EPA set standards based on the performance of actual
Yet EPA’s analysis does not reflect the performance of any actual sources. Instead, it is a compilation of the best data, for each pollutant, regardless of which source the data came from. As a result, the proposed rule’s limits are unnecessarily stringent. They do not reflect the variability that occurs in real-world.

There is no denying EPA failed to look at fuel types when establishing standards.  Rather, EPA went pollutant by pollutant and looked for the smallest emissions without considering the fuel being used in the boiler.

Genreal Industry Concerns

The biomass industry is just one of many industry sectors strongly opposing the rules.  The American Chemistry Council described the rules as "fundamentally flawed" in their comments:

“EPA’s faulty methodology begins with pollutant-by-pollutant analyses that select a different set of ‘best performing sources’ for each pollutant. In other words, EPA ‘cherry picks’ the best data in setting each standard, without regard for sources. The result is a set of standards achieved by a hypothetical set of ‘best performing’ sources able to maximize emission reductions for each hazardous air pollutant (HAP), rather than standards representative of actual performance of real sources. EPA’s approach produces unachievable standards."

How is EPA cherry picking its data?  Industry says EPA uses a limited data set of emissions from sources in establishing the standards. EPA has failed to test enough sources to truly reflect each category of sources.  Without a full or adequate data set, EPA is skewing the top 12% of best performing sources. It really becomes the top 12% of sources EPA tested, which can be a small percentage of boilers in use.

Furthermore, Industry argues EPA failed to account for variations critical when establishing a MACT standard.  Boilers can vary in design, pollution controls and fuels utilized. Industry argues these variations should have been considered in evaluating the top 12% performing sources.

[For more insight into industry’s general concerns here is a link to Ohio Chamber Comments]

Regulators Echo Industry Concerns

Industry is not alone in strongly criticizing EPA proposal.  Ohio EPA filed its own comments on the U.S. EPA proposed boiler MACT standards supporting the notion EPA’s methodology is flawed:

Limited Data Concerns:

[EPA’s] analysis seems to only utilize emission performance data from a limited number of sources and in some cases as few as one or two sources.  At a minimum a NESHAP standard needs to be based on the performance of five sources or all sources if fewer than five in a category.

Emission Standard Methodology

The emission limits proposed in the rule seem to be based on the lowest demonstrated emission rates within a source category (based on a limited number of sources) and does not directly evaluate control efficiency of equipment.  Using the emission rate approach may not identify the sources demonstrating the highest control efficiencies, but rather may simply reflect low fuel content of the pollutants.  In this case, resulting emission limits can be more stringent than achievable for sources utilizing certain fuels.

Impact on Fuel Types

EPA’s approach may be eliminating certain fuels from use in industrial boilers.  For example, midwest coal with higher sulfur or mercury content.  Or in the case of biomass, wood feed stocks that have already have lower hydrogen chloride (HCL) content, may not be able to remove additional quantities to achieve the low standards EPA is proposing.


EPA’s rule impacts such a huge portion of industry and commercial operations.  It should be carefully crafting a set of standards that are achieveable as well as flexible. Two final points:

  •  Not all pollution controls are appropriate for every sized boiler;
  • Restricting fuel types by establishing standards that discount pollutant content of those fuels does not reflect "real world" practices that NESHAP standards are intended to reflect.

(Photo:  U.S. EPA website)