EPA’s Boiler MACT: Controlling Emissions of Hazardous Air Pollutants

James E. McCarthy
Specialist in Environmental Policy

On December 2, 2011, EPA Administrator Lisa Jackson signed proposed revisions to EPA’s recently promulgated Maximum Achievable Control Technology standards for boilers (the “Boiler MACT”). Publication of the proposed revisions in the Federal Register will begin a 60- day public comment period, after which EPA will complete reconsideration of the rule – presumably by mid-2012. The Boiler MACT standards now being reconsidered were promulgated March 21, 2011, to meet the requirements of Section 112 of the Clean Air Act, but implementation has been stayed until completion of the reconsideration process. There is widespread interest in the rule’s requirements and their potential effects, because boilers are used as power sources throughout industry, and for power or heat by large commercial establishments and institutions as well.

EPA developed the regulations because it has found, based on emissions data, that boilers (including coal-, biomass-, and liquid-fired boilers) are major sources of hazardous air pollutants (HAPs). The Clean Air Act defines a major source as any facility that emits 10 tons or more of a single listed HAP or 25 tons of any combination of HAPs annually. The HAPs themselves (187 substances) were listed by Congress in the 1990 Clean Air Act Amendments.

When finalized, the rule will replace a 2004 version of the rule that was vacated and remanded to EPA by the D.C. Circuit Court of Appeals. EPA has been under a court order to promulgate a replacement.

As proposed December 2, the MACT would affect about 14,000 boilers and process heaters, with capital costs of $5.4 billion, according to the agency; annualized costs, which spread the costs of capital over the expected life of the equipment and include operating and maintenance expenses, are estimated at $1.49 billion per year. Most of these costs would be borne by boilers that burn coal, biomass, or liquid fuels; only 12% of all the units covered by the rule will need to install equipment to meet it. Most of the boilers affected by the rule (83%) are fueled by natural gas or refinery gases. These boilers would not have to install pollution control equipment and most would experience cost savings under the rule, according to EPA. For the rule as a whole, EPA estimated that benefits—including the avoidance of 3,100 to 8,000 premature deaths annually— would outweigh costs by at least $25 billion per year.

Affected industries and many in Congress have raised objections to the rule both as proposed and as promulgated, and bills have been introduced in both the House and Senate (H.R. 2250 and S. 1392) to alter the rule’s requirements and delay its implementation. H.R. 2250 passed the House 275-142, on October 13. In response to comments on an earlier proposal, EPA’s final rule had already reduced the number of units expected to require controls, and made the emissions standards much less stringent than those in the proposed rule, reducing the agency’s estimate of annualized control costs from $2.9 billion to $1.4 billion.

In addition to the Boiler MACT, this report discusses three related rules that EPA promulgated at the same time, dealing with smaller “area source” boilers and with commercial and industrial boilers that burn solid waste (the “CISWI” and solid waste rules). The latter two rules have also been controversial. Like the Boiler MACT, the CISWI rule has been stayed for reconsideration.


Date of Report: December 8, 2011
Number of Pages: 28
Order Number: R41459
Price: $29.95

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