Industrial Boiler MACT
The National Emission Standards for Hazardous Air Pollutants (NESHAP) for Industrial/Commercial/Institutional Boilers and Process Heaters (40 CFR Part 63, Subpart DDDDD), also known as the "Industrial Boiler MACT", is a complex set of emission standards and compliance requirements based on the application of maximum achievable control technology (MACT). While the rule affects both new and existing sources, the only existing boilers or process heaters that are affected, however, are large, solid fuel-fired units with a heat input rating greater than 10 MMBtu/hr and "limited use", solid fuel-fired units that operate less than 10% of capacity.
The rule was finalized on 2/26/04 and becomes effective 60 days after publication in the Federal Register. As of 7/9/04, EPA has indicated that the rule will be published very soon. Existing sources are allowed three years to comply but some sources may petition for an extra year to comply if additional time is required for the installation of controls. New industrial boilers and process heaters (built after 1/13/03) must comply with the new rule within six months of the effective date or six months after startup, whichever is later.
The final rule contains a variety of compliance provisions for emissions of carbon monoxide (CO), hydrogen chloride (HCl), mercury (Hg), particulate matter (PM) and "total selected metals" (TSM) the combination of arsenic, beryllium, cadmium, chromium, lead, manganese, nickel and selenium. Emission limits vary depending on unit size, fuel type, frequency of operation, and whether the source is new or existing.
The impact of the rule for existing sources will depend largely on whether the source is able to meet the new standards without the need of a control device. Sources that burn a relatively consistent fuel or fuel blend that can demonstrate compliance based on fuel analysis will likely find that the rule will have minimal impact. However, new sources and existing sources that are unable to demonstrate compliance based on fuel analysis will likely find the rule to be very costly to implement. These sources will have to conduct ongoing, expensive stack tests and meet prescriptive monitoring, reporting and record keeping requirements.
The rule affects all industrial, commercial, or institutional process heaters or boilers located at a facility that emits more than 10 tons/year of any one hazardous air pollutant (HAP) or 25 tons/year of any combination of HAP. Note that applicability is based on the facility emissions, not the individual units. Boilers or process heaters do not need to be a major source of HAP to be affected by the rule. The rule allows exemptions for the following types of units:
The rule includes emission standards for virtually all new units built after January 13, 2003, all existing large, solid fuel-fired units with a heat input rating greater than 10 MMBtu/hr and all existing, "limited use", solid fuel-fired units that operate less than 10% of capacity. While the rule also affects the following sources, these sources are only subject to limited initial notification requirements. The rule does not provide emissions standards for these sources.
In developing the emissions standards, EPA divided HAPs into the following four categories and selected a representative HAP for each category:
Affected sources may be subject to one or more of the regulated HAPs, depending on the classification of the boiler or process heater. Emissions standards for each regulated HAP also vary depending on the classification of the unit. There are 10 classifications or "subcategories" of affected units based on the age of the unit, fuel type, unit size, and frequency of operation. Tables 1 and 2 show each of the classifications, the regulated HAP(s) to which they are subject, and the corresponding emissions standard(s) for new/reconstructed and existing units. It is anticipated that virtually all new units and roughly half of the existing affected sources will require some form of emissions controls to meet the new standards.
The rule allows new and existing solid fuel-fired units to comply with either a total PM standard or a TSM standard. PM was proposed as a surrogate for TSM because non-mercury metallic HAPs exist in the flue gas combined with fly ash. EPA included both standards because, while all fuels emit particulate, not all fuels emit the same amount of metallic HAPs. Sources that burn fuels with a low TSM concentration would likely elect to comply with the TSM standard, instead of PM.
Table 1. Emissions Standards for New or Reconstructed Units
Table 2. Emissions Standards for Existing Units
As shown in Tables 3 and 4, the rule also includes alternative emission standards for large, sources that operate infrequently. In order to qualify for these alternative "limited use" standards, a source must have a federally enforceable annual average capacity factor less than or equal to 10 percent. Limited use, liquid fuel-fired units include those units that either burn only liquid fuel or regularly co-fire with a gaseous fuel. Use units that burn liquid fuel on a limited basis, during periods of gas curtailment or supply emergencies, are classified as limited use, gas-fired units.
Table 3. Alternative Emissions Standards for Limited Use New or Reconstructed Units
Table 4. Alternative Emissions Standards for Limited Use Existing Units
The rule provides two primary mechanisms for demonstrating initial and ongoing compliance. All sources have the option of complying with each applicable emission limit using either a fuel-based or stack emission-based approach, although the fuel-based approach is preferred because of the simplified compliance requirements. Virtually all new solid fuel-fired sources, however, and many existing sources will be unable to meet these requirements. Existing units likely to be affected by the rule include those that fire bituminous coal, which typically has higher mercury and chlorine concentrations.
In order to demonstrate initial and continuous compliance using the fuel-based approach, a fuel analysis must be conducted which shows that the pollutant concentration of the combusted fuel is below the applicable limit. Sources that co-fire fuels must demonstrate that the prorated pollutant concentration of the fuel blend is below the applicable limit. Once a source demonstrates initial compliance, additional fuel sampling is required every five years or whenever the source changes fuel type or fuel blends. A change in fuel vendor does not constitute a change in fuel type. Examples of fuel type switching include burning a different rank of coal, burning pet-coke blends, or switching between coal and some other type of solid fuel (or vice versa). Stack testing is not required for sources using the fuel-based approach.
Stack Emission-Based Approach
The stack emission-based compliance procedures, which are much more complicated, implement a "test and cap" approach. Sources are required to perform an initial stack test while combusting fuel containing the highest expected concentration of the applicable pollutant. During the stack test, the source must also perform fuel sampling and collect control device operating data to define the normal operating range of the control device during the test (except for units equipped with only a baghouse or electrostatic precipitator (ESP)). Initial compliance is based on the stack test results. Continuous compliance is based on (1) maintaining the fuel pollutant concentration below the level that was measured during the initial test and (2) maintaining control device operating parameters within the limits observed during the initial test (except for units equipped with only a baghouse or ESP). Units equipped with an ESP as the only control device must maintain opacity below 20% for existing sources or 10% for new sources in order to demonstrate compliance. If a unit is unable to demonstrate compliance with the 20% opacity limit, unit-specific testing may be conducted to determine a more appropriate opacity limit for the unit. Units equipped with a baghouse as the only control device have the option of complying with the same opacity requirements as ESPs or may demonstrate compliance by using a bag leak detection system.
Sources electing to use the stack emission-based approach are required to conduct additional stack testing every year for three years. If a source is able to demonstrate compliance for three consecutive years, then the source is eligible to conduct compliance testing thereafter every three years. If the source fails any of these subsequent tests, they must again conduct additional tests every year until they achieve three consecutive years of compliance. Also, if a source changes fuel types, they must conduct another compliance test for that fuel or fuel mixture. One of the more onerous requirements of the rule is that sources must conduct additional fuel sampling (even if the fuel type is the same) and reestablish or verify control device indicator ranges with each ongoing compliance test.
One of the major changes from the proposed rule is the addition of emissions averaging provisions. Emissions averaging may only be used for existing large, solid fuel-fired boilers and with the permission of the state agency. Sources with multiple affected units that are likely to implement emissions averaging include (1) sources with one or more units that are unable to demonstrate compliance using the fuel-based approach and (2) sources with one or more units that are unable to demonstrate compliance using the stack emissions-based approach, without upgrading or replacing existing control equipment.
Emissions averaging procedures can be applied using either the fuel-based or stack emission-based methods. The initial compliance procedures require the source to calculate the average weighted emissions for the averaging group by weighting the emissions rate of each unit (either by fuel analysis or stack test results) by the individual rated heat input capacity. In order to demonstrate initial compliance, the average weighted emissions must be less than the applicable emission limit.
Ongoing compliance is demonstrated based on a 12-month rolling average using a similar procedure. Each calendar month, the source must calculate the average weighted emissions of the averaging group by weighting the emissions rate of each unit (using the result of the last fuel test or stack test) by the average heat input of each unit during that calendar month. In order to demonstrate compliance, the average weighted emissions must be less than the applicable emission limit. The rule provides similar procedures based on steam generation for units that can not monitor heat input. Unlike the proposed utility boiler MACT averaging procedures, there are no specific requirements for data availability or minimum operating time of the individual units.
The emissions averaging provisions also include a requirement to establish indicator ranges and monitor the operation of the control device(s) used to comply with the applicable limit. Although the language in this section is unclear, it appears that the monitoring requirements are the same as those for units that do not implement emissions averaging, and apply to averaging groups that use either fuel-based or stack emission-based compliance approaches. It is important to note that emissions averaging procedures do not permit sources to de-tune or otherwise reduce the efficiency of the control devices during the initial compliance test
Sources electing to use emissions averaging must submit an averaging plan no later than 180 days prior to the initial compliance test.
Health-Based Compliance Alternative for HCl and TSM
In addition to the "technology-based" MACT compliance approach, EPA has included an alternative "health-based" or "risk-based" approach for HCl and TSM emissions. These compliance approaches do not require any ongoing compliance tests, monitoring, or reporting/recordkeeping. While the benefits of using these alternative compliance criteria may seem attractive, sources are required to incorporate the process parameters (heat input, flow rates, fuel flow, etc.) used to demonstrate compliance into the Title V operating permit. These operating conditions then become Federally enforceable and may limit subsequent operation of all units at the facility.
For HCl emissions, sources must conduct HCl and chlorine emission tests for all affected units at the facility and calculate an equivalent maximum, hourly HCl emission rate. The rule provides maximum acceptable facility-wide emission rates based on stack height and the distance between the stack and the property boundary. If the calculated hourly HCl emission rate for the facility is below the accepted maximum value, then the facility is eligible to use the alternative compliance criteria. However, if the facility is unable to meet the maximum accepted emissions value, the source may conduct a risk-assessment analysis for the facility. In this case, in order to use the alternative compliance criteria, the risk-assessment must demonstrate that the facilitys hazard index for HCl and chlorine emissions is less than one.
The alternative compliance criteria for TSM is similar to that for HCl, except manganese is used as a surrogate for TSM emissions. Sources must first test all affected units to determine the maximum emission rate of manganese for the facility. If the facility emission rate is below the allowable value, based on stack height and property boundary proximity, then the source is eligible to use the alternative compliance criteria. Alternatively, the source may conduct site-specific testing to demonstrate that the facilitys hazard index for manganese is less than one.
For sources that demonstrate compliance using the stack emission-based approach, the new rule includes prescriptive monitoring requirements and ongoing monitor quality assurance activities. These requirements will be very costly to implement for sources without existing continuous monitoring systems (for sources that are required to demonstrate compliance with a CO or opacity limit) or modern control systems on their emissions control equipment.
The rule requires that monitoring systems automatically reduce the data to three-hour averages (as applicable) to demonstrate continuous compliance. This means that although many existing sources already have a CPMS, CEMS, or COMS, they will need to reprogram the systems to provide the appropriate averaging period. The monitoring provisions do not include procedures for handling missing data. Averages are based on the available quality assured data, excluding calibration checks, span adjustments, repairs, or monitor malfunctions. Any period where the monitor is out-of-control constitutes a deviation from the monitoring requirements and must be included in the semi-annual compliance reports.
Reporting and Recordkeeping Requirements
The new rule also contains an array of reporting and recordkeeping requirements. Affected sources must maintain records of control device operating data, monthly fuel consumption and type(s) of fuel burned, operating hours, unit startups and shutdowns, CEMS calibration data, CEMS maintenance events, CEMS out of control periods, fuel sampling reports, information on compliance deviations (including a description of the deviation, the duration of the deviation, and any corrective action that was taken), and a number of other pieces of information. Sources must maintain this data onsite for a period of five years. Sources are also required to submit semi-annual compliance reports that include much of this information, although the rule does not specify a standardized data format (e.g. Part 75 electronic data reports).
Given the amount of data that is involved in demonstrating compliance, it is likely that this portion of the rule will be very costly and complicated to implement, particularly for sources with multiple affected units. Many sources will need to install CEMS, COMS, and/or CPMS. These systems will need to be programmed to track monitor downtime, unit start-up and shutdown, monitor maintenance activities, and compliance deviations. Additional resources will be required to gather other compliance data that may not available in electronic format, such as fuel analysis reports and fuel consumption data, and prepare compliance reports.
Compliance Deadline Summary
Table 5 contains a summary of the various compliance requirements and the associated deadlines.
Table 5. Summary of Compliance Deadlines
RMB Recommendations for Newly Affected Sources
RMB offers a wide variety of services to assist sources in complying with the requirements of the industrial boiler MACT including:
Agora Environmental Consulting