MACT Update: Details on Boiler, Process Heater, Combustion Turbine and Internal Combustion Standards
By Thomas R. Wood
On May 20, 2002, the EPA staff working on the reciprocating internal combustion engine ("RICE") MACT, the boiler/process heater MACT and the combustion turbine MACT took part in a national broadcast organized by the A&WMA. This seminar featured a wealth of information about the impending standards.
Maximum achievable control technology ("MACT") is the level of control required for hazardous air pollutants ("HAPs") under section 112 of the Clean Air Act. Generally this standard only applies to sources that are considered major sources of HAP, i.e., sources with the plant-wide potential to emit more than 10 tons per year of any individual HAP or 25 tons per year of aggregate HAPs. EPA promulgates MACT standards on both an industry type basis (e.g., fiberglass boat manufacturing) and a process type basis (e.g., cooling towers). Currently, EPA is working on dozens of MACT standards trying to beat a deadline that, as it currently stands, is set for May 2004 (that may change as the result of recent litigation). Three standards under development with the greatest potential impact are the RICE MACT, the boiler/process heater MACT and the combustion turbine MACT. These standards will apply to the majority of industrial source that are major HAP sources. Industry has waited, with some trepidation, to hear what sort of controls EPA would propose for these categories. At the May 20 presentation, EPA revealed the following high (and/or low) points about the proposed standards.
The RICE MACT will apply only to stationary RICE which (1) are located at a source that is major for HAPs and (2) have a manufacturer's nameplate rating of 500 brake HP or more. Units used exclusively for emergency purposes or for less than 50 hours per year will be excluded. Limits will be proposed for existing four stroke rich burn engines and for new four stroke rich burn engines, two and four stroke lean burn engines, and compression ignition engines. New source limits will allow source to either install CO catalysts or document formaldehyde reductions. CO catalyst performance requirements vary with the type of unit. Testing, monitoring and operational requirements will be stricter for those engines over 5,000 brake HP. For example, units over 5,000 brake HP that choose the CO catalyst option must install and operate a CO continuous emission monitoring system ("CEMS"). EPA predicts that there will be 1,840 existing RICE and 8,400 new RICE (by 2008) that are affected by the rule. The RICE MACT is expected to be proposed for public comment this fall and promulgated in November 2003.
BOILER & PROCESS HEATER MACT
The boiler & process heater MACT will probably be the most widely felt of all the MACTs with EPA anticipating that it will apply to 42,000 boilers and 15,000 process heaters. MACT will only apply to boilers or process heaters located at sources that are major sources for HAPs. It cannot be emphasized enough that the entire source's emissions are used for determining HAP major source status, not just the boiler or process heater emissions. In determining what constitutes a "process heater," the most important criterion is that in a process heater the combustion gases do not come into contact with process gases or process materials in the combustion chamber. If a combustion unit is or will be covered by another MACT standard, it is not supposed to be covered by this MACT (e.g., recovery boilers, municipal waste combustors).
The boiler and process heater MACT will be most keenly felt by units that burn solid fuel. EPA indicated that the proposed rule will categorize boilers/process heaters that burn any amount of solid fuel as solid fuel-fired boilers. MACT for existing solid fuel fired boilers with a nameplate capacity greater than 10 million Btus per hour ("MMBtu/hr") will be based upon the use of both a baghouse and a scrubber. Particulate, hydrogen chloride and mercury limits will be proposed of 0.07 lb/MMBtu, 0.09 lb/MMBtu and 4 lb/trillion Btu, respectively. While the MACT standard will be an emission limit, not a mandatory technology, usually the emission limits are constructed in such a way that it is challenging to adequately control emissions any other way. Continuous opacity monitors ("COMs") will be required. Limited use solid fuel-fired boilers (i.e., units that operate less than 10% of their capacity factor) are expected to "only" be required to install electrostatic precipitators. Existing boilers that burn exclusively gas and/or liquid fuel, as well as existing solid fuel-fired boilers with a nameplate capacity of less than 10 MMBtus/hr, are not expected to be subject to any MACT limits.
New boilers and process heaters will be more broadly and stringently limited. MACT is expected to be proposed for new solid fuel-fired units so as to limit particulate, hydrogen chloride, mercury and carbon monoxide to 0.01 lb/MMBtu, 0.02 lb/MMBtu, 1 lb/trillion Btu and 400 ppm (3% oxygen), respectively. COMs, CO CEMs and parametric monitoring will be required under the proposed standard. The proposed standards will anticipate that both solid and liquid fuel new units will require baghouses and scrubbers regardless of boiler size. The only dispensation for smaller new liquid or solid fuel units under the proposed rule is that units with a nameplate capacity of 10 MMBtus/hr or less will not be subject to the CO limit or associated continuous monitoring requirement.
Many new gas fired units will not escape the MACT requirements. New units burning exclusively gas with a nameplate capacity of 10 MMBtus/hr or less will not be subject to requirements under the proposed MACT. However, new units burning exclusively gas with a nameplate capacity of greater than 10 MMBtus/hr will be subject to the CO limit and continuous monitoring requirements.
This rule is expected to be proposed for public comment in August 2002 and the final rule issued in November 2003.
COMBUSTION TURBINE MACT
The combustion turbine ("CT") MACT will apply to stationary combustion turbines located at HAP major sources with a rated peak power output of greater than 1.0 MW. Emergency turbines, turbines burning primarily landfill gas or digester gas, turbines operated less than 50 hours per year and existing diffusion flame turbines will not be subject to limits under the MACT, but will still be covered for purposes of notification. The MACT is expected to be proposed as requiring compliance with either a 95% reduction of CO from the turbine exhaust using a CO catalyst, or reduction of formaldehyde emissions to 25 ppbvd (yes, we mean ppbvd) or less. If you choose to meet the new turbine CO limit, then the proposed rule will require a CO CEMS monitoring upstream and downstream of the catalyst to document the 95% destruction and removal efficiency. Monitoring requirements for new units complying with the formaldehyde limit vary by type. No initial compliance requirements will be proposed for existing lean premix combustor CTs.
This rule is expected to be proposed in September 2002 and the final rule issued in November 2003.
These three MACTs only apply to facilities that are HAP major sources. If your facility is a HAP minor source, i.e., your potential to emit any single HAP is less than 10 tons per year and your potential to emit total HAPs is less than 25 tons per year, you need not be concerned about these rules. However, as always, it is important to ensure that you have accurately and completely estimated your HAP potential to emit. If your HAP potential to emit would be over the major source levels but for controls or some assumed limit, make sure you have a signed applicability determination in your files outlining why the MACT does not apply.
Because of the sweep of these three MACT standards, and the degree of impact they could have on new and existing sources, it is critical that affected facilities consider commenting on the proposed rules. This is the one opportunity sources have to affect EPA's approach. Comments will be particularly important for sources with affected boilers given the variety of equipment configurations.
For Additional Information, Contact: Tom Wood, Stoel Rives LLP at 503-294-9396.
Originally published in June 1, 2002 edition of Oregon Insider.