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Impact on Industry
The EPA estimates that there are more than 13,500 boilers and process heaters located at major HAP sources that will be subject to the Industrial Boiler MACT Rule. A majority—approximately 11,500—of these boilers fire natural or refinery gas and, therefore, will be subject only to the rule's work-practice standards. However, there still are approximately 2,000 boilers that will have to comply with the rule's emissions limits.

The rule is expected to have the most significant impact on facilities that utilize coal- or biomass-burning boilers (solid-fuel-fired boilers). The EPA estimates there are approximately 600 coal-fired boilers and 400 biomass-fired boilers that will be affected by the rule. Many of the solid-fuel-fired boilers in compliance with the original 2004 rule will not be in compliance with the new rule's more stringent emission limits (Table 2). The stringent emission limits may force owners of solid-fuel-fired boilers to significantly upgrade their existing pollution-control equipment or consider switching to natural gas.

The PM limit will require most boilers to have a fabric filter as a particulate-control device. Of the approximately 600 coal-fired boilers, fewer than 200 utilize fabric filters. The HCl limit will require many solid-fuel-fired boilers to install scrubbers or inject an alkaline sorbent (hydrated lime, trona, etc.) ahead of the particulate-control device. The Hg limit also will require many boilers to install powdered-activated-carbon-sorbent injection systems ahead of the particulate-control device.

The CO and dioxin/furan limits will pose an additional challenge for most boiler owners because little emissions testing has been conducted to help owners understand the magnitude of these emissions or how best to control them. Therefore, total air-pollution-control upgrades for an existing solid-fuel-fired boiler could take many forms, including the retrofit of sorbent injection systems, a fabric filter, or a scrubber, at minimum. The cost of boilers will vary greatly, depending on size, fuel type, the extent and condition of existing pollution-control equipment, and retrofit complexity. Capital costs for these modifications could range from $1 million or less for a sorbent injection system to $5 million to $10 million or more for a fabric filter or scrubber. The EPA estimates that the average capital cost of retrofitting a coal-fired boiler with pollution-control equipment to meet emissions limits will be nearly $8 million, and the average capital cost of retrofitting biomass-fired boilers will be nearly $5 million.

Conclusion
Each compliance situation is unique. The only way to know what modifications may be necessary is to conduct a compliance study establishing baseline emissions information and comparing it with Industrial Boiler MACT Rule emissions limits. Because many facilities do not understand the magnitude of their emissions, compliance studies likely will include stack testing to establish baseline emissions, which a facility can use to assess compliance and, if necessary, develop a plan of corrective action.

Facilities must begin planning now. The Industrial Boiler MACT Rule compliance date is expected to be in late 2013 or early 2014. Generally, a compliance study takes six months, and air-pollution-control retrofit projects/fuel-switching projects can take 18 months to three years from the start of compliance planning through engineering and construction to startup.

Don Wolf is a principal with Burns & McDonnell Engineering Co. He manages the company's Energy Global Practice in its St. Louis, Mo., regional office. He can be reached at dwolf@burnsmcd.com.

Did you find this article useful? Send comments and suggestions to Associate Editor Megan White at megan.white@penton.com.

In related regulation news...

The EPA also proposed a rule on April 29 that would reduce emissions of toxic air pollutants from existing and new industrial, commercial, and institutional boilers located at Area Source facilities. An Area Source facility emits or has the potential to emit less than 10 tons of any single air toxin per year or less than 25 tons of any combination of air toxins per year. The rule would cover boilers that burn coal, oil, or biomass and establish standards to address emissions of Hg, PM (as a surrogate for non-mercury metals), and CO (as a surrogate for organic air toxics).