EPA Finalizes Hazardous Air Emission Rules for Boilers and Process Heaters Affecting 90,000 Facilities
EPA’s standards for hazardous air emissions from boilers and process heaters, commonly referred to as “Boiler MACT,” were formally published on January 31, 2013. Boilers and heaters that were constructed after June 4, 2010 must meet the new requirements immediately; older units must come into compliance over the next three years, unless continued litigation derails this rule once again. Boilers and process heaters are common components of a wide variety of industrial facilities – refineries, pulp and lumber mills, food processors, chemical manufacturers, smelters, glass makers, and other factories – as well as large institutional facilities like universities and hospitals. EPA estimates that under its new rules about 200,000 boilers and heaters at about 90,000 facilities will be subject to new work practice standards. About 14,500 existing boilers and heaters located at about 1,700 existing facilities also will be subject to new emission limits.
Boiler MACT’s most significant impacts fall on solid and liquid-fueled boilers and process heaters – those powered by coal, biomass, and oil. They are subject to new emission limits for filterable particulate matter (metals), carbon monoxide, mercury, and hydrogen chloride (acid gases). In addition, most boilers and process heaters that run on any type of fuel, including natural gas, will be required to undergo regular tune-ups. Some facilities also will be required to conduct a one-time energy assessment designed to identify cost-effective ways to improve the efficiency of the units.
Past Efforts to Develop Boiler MACT Rule
In 2004, EPA adopted a MACT standard for industrial and commercial boilers and process heaters located at facilities that have combined emissions from all sources that make them a major source of hazardous air pollutants, commonly referred to as “Boiler MACT.” In 2007, the D.C. Circuit Court of Appeals vacated the Boiler MACT standard because it found EPA had differentiated between incinerators (subject to section 129 of the Act) and boilers (subject to section 112) in a way that conflicted with the intent of the statute. There also were challenges to the substance of the standard from both industry and environmental interests, but those were left unresolved by the court’s decision.
EPA then launched a rewrite of the Boiler MACT standard, and issued a new proposed rule in 2010. Once again the rule was controversial, but EPA was under a court-ordered deadline to complete its work and adopt a final standard. EPA asked the court for more time, but that request was denied. EPA then adopted a final version of the Boiler MACT standard in March of 2011, but in the same issue of the Federal Register the Agency announced that it intended to reconsider fourteen specific issues related to the rule, and to take additional comment on those issues. EPA also immediately received petitions to reconsider various other aspects of the Boiler MACT standard, and the rule was challenged in court.
The version of the Boiler MACT standard adopted in 2011 would have set limits for emissions of mercury, dioxin, particulate matter, hydrogen chloride and carbon monoxide for all new and existing large boilers, and applied to units burning coal, fuel oil, natural gas or biomass. It also would have set limits on mercury and carbon dioxide from smaller boilers, but only if they burn coal, but required regular tune-ups for boilers at a very large number of smaller facilities.
As adopted, the Boiler MACT standard would have taken effect on May 20, 2011. But EPA, bowing to pressure from a variety of sources, announced on May 18, 2011 that the effective date of the rule was delayed until EPA could complete its reconsideration of the rule or until judicial review of the rule is no longer pending, whichever was earlier.
In December 2011, EPA published another proposed re-write to the Boiler MACT rule, responding to issues it had agreed to reconsider. This time EPA issued separate proposals for boilers and heaters at facilities that are major sources of hazardous air pollutants and for those located at “area” sources of hazardous air pollutants. EPA then took public comment on these further proposed revisions before issuing the most recent final version of the Boiler MACT rule.
Because of the widespread impact of the Boiler MACT rules, there is likely to be further litigation over this standard. But absent action by the courts staying EPA’s final version of the regulations, facilities with boilers and heaters that are subject to the rule must now begin to implement its requirements.
Boiler MACT’s Requirements
Boiler MACT actually consists of two rules, one for boilers and process heaters located at facilities that – when all emission sources are combined – are a “major source” of hazardous air pollutants, and the other for boilers and heaters located at an “area source.” The “major source” threshold is 10 tons per year of any one hazardous air pollutant, or 25 tons of all hazardous air pollutants combined. Any facility with combined emissions below the major source threshold is an “area source.”
The Boiler MACT rules identify 19 different subcategories of boilers and heaters, based on unit design and fuel type. Units fueled by natural gas are only subject to work practice requirements, consisting of regular tune-ups and, for existing units at major sources, a one-time energy assessment. Boilers and heaters powered by solid and liquid fuels (coal, biomass and oil) are subject to the same work practice requirements, and also to new emission limits. Many of the emission limits have changed from the March, 2011 version of the Boiler MACT rule. Some have become more stringent, and others less stringent.
Work Practice Requirements
A one-time energy assessment is required for all existing boilers and process heaters (regardless of fuel type) located at a major source of hazardous air pollutants, and for larger existing boilers and heaters (10 million Btu/hr or more) located at area sources that are fueled by coal, biomass, or oil. The assessment must include:
- Structural elements – a visual inspection of the boiler or process heater, a review of available architectural and engineering plans, a review of operating characteristics and any unusual operating constraints, a review of facility and boiler/process heater operation and maintenance procedures, and review of logs and fuel usage;
- Energy use – an inventory of major energy consuming systems, a review of the facility’s energy management practices;
- Recommendations – recommendations for improvements, a list of major energy conservation measures and the energy savings potential for each measure;
- Report – detailing ways to improve efficiency, the cost of specific improvements, benefits, and the time frame for recouping the investment.
Tune-ups are required for most boilers and process heaters at major sources and for units at area sources that burn coal, oil, or biomass, with varying frequency for different fuel types and designs. A tune-up must include inspecting the burner (cleaning and replacing parts as necessary), inspecting the flame pattern (adjusting as necessary), inspect the system that controls air/fuel ratio (calibrate or adjust as necessary), and optimize carbon monoxide emissions. Carbon monoxide and oxygen concentrations must be measured in the exhaust before and after the tune-up. At major sources:
- Annual tune-ups are required for boilers and heaters over 10 million Btu/hr that are not equipped with controls to continuously optimize air/fuel ratio.
- Biennial tune-ups are required for heavy liquid and solid-fueled boilers and heaters smaller than 10 million Btu/hr, and gas and light liquid-fueled boilers and heaters between 5 and 10 million Btu/hr that are not equipped with continuous air/fuel ratio controls;
- Tune-ups every five years are required for new and existing boilers that burn natural gas or light liquid fuels and are smaller (less than 5 million Btu/hr) or have continuous controls to optimize air/fuel ratios, as well as limited use boilers;
Boilers and process heaters at area sources that burn coal, biomass, or oil also are required to conduct regular tune-ups. Biomass-fueled units, coal-fired units smaller than 10 million Btu/hr, and oil-fired units larger than 5 million Btu/hr are required to conduct tune-ups biennially. Seasonal and limited used boilers and process heaters at area sources, as well as smaller oil-fired units (less than 5 million Btu/hr) and units with controls to continuously optimize air/fuel ratios, require tune-ups every five years.
For boilers and process heaters at major sources that burn solid fuels (coal or biomass), the Boiler MACT rule imposes emission limits with 13 variations for different boiler configurations and fuel types, limiting carbon monoxide, mercury, hydrogen chloride as a surrogate for acid gases, and filterable particulate matter (or alternatively, total suspended metals). For oil-fired boilers at major sources, Boiler MACT limits the same air pollutants, differentiating between light and heavy oil fueled-boilers for the limits on filterable particulate matter (metals) and carbon monoxide.
At area sources, Boiler MACT imposes emission limits on boilers and process heaters larger than 10 million Btu/hr that burn coal (both new and existing units), biomass (new units only), or oil (new units only). New coal-fired boilers receive limits on mercury, carbon monoxide and filterable particulate (with more stringent particulate limits for units over 30 million Btu/hr). Existing coal-fired boilers receive limits on carbon monoxide and mercury emissions. New biomass-fired units receive limits on filterable particulate emissions (with a more stringent limit for units over 30 million Btu/hr). Oil-fired boilers also receive limits on filterable particulate emissions. Boiler MACT’s emission limits for boilers and process heaters at area sources do not apply to limited use boilers.
Any boiler or process heater subject to Boiler MACT that was constructed after June 4, 2010 is considered a “new source” under the rules. This is the date that EPA published its proposed Boiler MACT rules, after the first version of the rule was rejected by the D.C. Circuit Court of Appeals.
Boiler MACT also requires annual performance tests for units at major sources that are subject to emission limits, and allows performance to be demonstrated by monthly fuel analysis rather than annual emissions tests for chloride, mercury, and total suspended metals. At area sources, boilers and process heaters larger than 10 million Btu/hr must have performance tests every three years.
Many industrial facilities that use oil, biomass, or coal to fuel their boilers will now face significant costs for new controls on existing boilers and process heaters to meet the rule’s new emission limits. But the impact of the new rule is more widespread. It requires periodic tune-ups of approximately 200,000 boilers and process heaters at thousands of facilities. The affected facilities also have regular reporting and recordkeeping requirements, which could prove to be a compliance problem for some smaller sources that are not usually subject to EPA’s regulatory requirements.
Perhaps the most interesting element of Boiler MACT is the requirement for one-time energy assessments for existing boilers and process heaters at major sources and for larger existing units at area sources. The rule does not require facilities to implement the energy conservation measures identified through the assessment process. However, the expectation is that many facilities will implement those measures that have a reasonably short time frame for recouping the necessary investment.
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