Emergency Generators: “Miscellaneous Sources” or Federally Regulated Combustion Units?
Posted: January 13th, 2012Author: All4 Staff
Are you planning to install a new emergency generator or modify an existing emergency generator at your facility? Do you currently operate an emergency generator at a facility that is a major source of hazardous air pollutants (HAPs)? If you answered yes to either of these questions, you will likely need to comply with the following Federal regulations pertaining to internal combustion engines (ICE):
- 40 CFR Part 60, Subpart IIII – Standards of Performance for Stationary Compression Ignition (CI) Internal Combustion Engines (ICE).
- 40 CFR Part 60, Subpart JJJJ – Standards of Performance for Stationary Spark Ignition (SI) ICE.
- 40 CFR Part 63, Subpart ZZZZ – National Emission Standards for Hazardous Air Pollutants (NESHAP) for Stationary Reciprocating Internal Combustion Engines (RICE).
Read on as Colin McCall and Glenn Watson of ALL4 provide a general review of the New Source Performance Standards (NSPS) and NESHAP rules that regulate emissions from the ICEs that drive most emergency generators, including a discussion that addresses the following aspects of the rules:
- Emission Requirements;
- Operating Requirements;
- Testing requirements;
- Monitoring, reporting, and recordkeeping requirements; and
- Fuel requirements and specifications.
40 CFR Part 60, Subpart IIII – Standards of Performance for Stationary Compression Ignition Internal Combustion Engines
Subpart IIII became effective on September 11, 2006 and applies to all stationary CI ICE (i.e., non-emergency generators, emergency generators, and fire pumps) that are modified, reconstructed, or ordered by a facility after July 11, 2005. A stationary ICE is defined as any ICE, except combustion turbines, that converts heat energy into mechanical work and is not mobile. Emergency stationary ICE are those engines for which operation is limited to emergency situations and required testing and maintenance (with readiness testing and maintenance checks limited to 100 hours per year).
Generator sets or fire pumps with an engine displacement of less than 30 liters per cylinder are subject to the CI ICE rule if they are model year 2007 or later. There is no engine size applicability threshold for Subpart IIII.
The emission limits and percent reduction requirements that apply to stationary CI ICE depend upon a combination of the following CI ICE specifications:
- Engine type (i.e., emergency, non-emergency, fire pump);
- Rated engine power (kW or HP);
- Rated engine speed (rpm or Hz);
- Engine displacement (liters per cylinder); and
- Engine model year.
For example, the owner of a model year 2006 non-emergency stationary CI ICE with a displacement of less than 10 liters per cylinder and a maximum engine power greater than 50 HP but less than 75 HP would be required to meet an emission standard of 6.9 g/HP-hr for oxides of nitrogen (NOX). Emission limits also exist for particulate matter (PM), carbon monoxide (CO), hydrocarbons (HC), and non-methane hydrocarbons (NMHC).
Emission testing requirements for owners and operators of stationary CI ICE will vary depending upon the displacement of the engine. In general, owners and operators of a stationary CI ICE with a displacement of less than 30 liters per cylinder are not required to conduct performance testing. Performance tests of these engines would typically be performed by the engine manufacturer. Owners and operators of a stationary CI ICE with a displacement of greater than or equal to 30 liters per cylinder are required to conduct performance tests utilizing U.S. EPA test methods. Each performance test must be conducted within 10 percent of 100 percent peak (or highest achievable) load. Performance tests may not be conducted during periods of startup, shutdown, or malfunction, and three (3) separate test runs of at least one (1) hour in duration must be conducted. Testing requirements are also specified for determining compliance with the percent reduction requirements.
Monitoring, Recordkeeping, and Reporting Requirements
The following monitoring, reporting, and recordkeeping requirements could apply to CI ICE that drive emergency generators or fire pumps depending on their model year and engine size:
- CI ICE should be equipped with a non-resettable hour meter.
- Any CI ICE with diesel particulate filter control must be equipped with a backpressure monitor.
- If performance testing is not required for the ICE (i.e., the engine has a displacement of less than 30 liters per cylinder), then the facility must confirm that the manufacturer-provided engine is designed to meet Subpart IIII emission limits.
- Except for emergency CI ICE, all facilities must submit an initial notification of rule applicability. The contents of the initial notification will depend on engine size and engine model year.
- Facilities must maintain records of manufacturer documentation specifying that applicable engines meet Subpart IIII emission limits.
- Facilities must maintain records of maintenance performed on the engine, with certain exceptions based on maximum power output and model year of the engine.
The following fuel requirements apply to all stationary ICEs regulated under Subpart IIII that use diesel fuel:
- Engines must use only diesel fuel that has a maximum sulfur content of 500 ppm (0.05% by weight). In addition, the diesel fuel must have a minimum cetane index of 40 or maximum aromatic content of 35 percent by volume.
- Beginning October 1, 2010, engines must use only diesel fuel that has a maximum sulfur content of 15 ppm (0.0015% by weight). In addition, the diesel fuel must have a minimum cetane index of 40 or a maximum aromatic content of 35 volume percent.
The Subpart IIII diesel sulfur limits are lower than limits that apply to most existing combustion related equipment. Therefore, any new or modified engines located at a facility that has historically combusted higher sulfur diesel fuel in other combustion sources could encounter diesel fuel logistic and storage issues given the differing fuel sulfur requirements. In certain instances, facilities may elect to shift entirely to lower sulfur diesel for all combustion sources since installing new storage tanks or filling different storage tanks with different fuels may not be feasible.
40 CFR Part 60, Subpart JJJJ – Standards of Performance for Stationary Spark Ignition Internal Combustion Engines
There are several applicability cutoff dates for Subpart JJJJ, but generally any SI ICE modified, reconstructed, or ordered by a facility after June 12, 2006 is subject to Subpart JJJJ requirements. Similar to Subpart IIII, there is no engine size applicability threshold under which Subpart JJJJ would not apply.
The emission limits and percent reduction requirements that apply to a stationary SI ICE will depend upon a combination of the following parameters:
- Engine type (i.e., rich burn or lean burn);
- Rated engine power (kW or HP);
- Fuel (i.e., gasoline, liquefied petroleum gas, natural gas, wellhead gas, landfill/digester gas); and
- Date of engine manufacture/modification/reconstruction.
For example, the owner of a 100 HP, gasoline fueled stationary SI ICE that was manufactured on or after January 1, 2009 would be required to meet an emission standard of 2.0 g/HP-hr for HC and NOX and 3.3 g/HP-hr for CO.
Facilities that choose to comply with Subpart JJJJ via performance testing must do so in accordance with U.S. EPA test methods. Each performance test must be conducted within 10 percent of 100 percent peak (or highest achievable) load. Performance tests may not be conducted during periods of startup, shutdown, or malfunction, and three (3) separate test runs of at least one (1) hour in duration must be conducted. In addition, the owner or operator must follow requirements for determining compliance with the mass per unit output emission limitations for NOX, CO, and VOC.
Monitoring, Reporting, and Recordkeeping Requirements
Although several combinations of monitoring, reporting, and recordkeeping requirements exist for SI ICE, the requirements are largely similar to those described for Subpart IIII above. These requirements include installing a non-resettable hour meter, documenting compliance with the Subpart JJJJ emission limits, submitting an initial notification of rule applicability, and tracking maintenance activities performed on the engines.
Subpart JJJJ includes sulfur limits for all SI ICE that use gasoline. However, all fuel sulfur limits apply only to refiners and importers of gasoline.
40 CFR Part 63, Subpart ZZZZ – NESHAP for Stationary Reciprocating Internal Combustion Engines
Subpart ZZZZ applies to any stationary RICE that is located at either major or area sources of HAPs. Similar to the Part 60 ICE regulations, no engine size applicability threshold exists for Subpart ZZZZ, although most of the Subpart ZZZZ requirements apply to stationary ICE operated at facilities that are major sources of HAPs.
Emissions and Operating Requirements
The emission limits and operating requirements that apply to stationary RICE depend upon a combination of the following parameters:
- Engine status (i.e., existing, new, reconstructed);
- Engine type (i.e., four-stroke rich burn, four-stroke lean burn, two-stroke lean burn);
- Engine site rating (brake HP);
- Date of engine manufacture; and
- Presence or absence of non-selective catalytic reduction (NSCR).
For example, the owner of a four-stroke, rich burn stationary RICE using NSCR would be required to limit the concentration of formaldehyde in the engine’s exhaust to 350 ppbvd or less at 15 percent O2, and to maintain the temperature of the engine’s exhaust so that the catalyst inlet temperature is greater than or equal to 750 °F but less than 1,250 °F. Similar emission limits exist for CO.
Depending on the engine-specific parameters described above, performance testing in accordance with U.S. EPA test methods may be required. Each performance test must be conducted within 10 percent of 100 percent load. Performance tests may not be conducted during periods of startup, shutdown, or malfunction, and three (3) separate test runs of at least one (1) hour in duration must be conducted. Requirements are also in place for determining compliance with the percent reduction requirement and for normalizing CO or formaldehyde concentrations at the inlet and outlet of the engine’s control device.
In certain cases, the owner or operator of a stationary RICE will be required to petition the Administrator for operating limits to be established during the initial performance test and continuously monitored thereafter, or for approval of no operating limits. Applicability of this provision will depend upon the emission limits that the owner or operator is complying with, as well as on the use or absence of an oxidation catalyst or NSCR.
Monitoring, Reporting, and Recordkeeping Requirements
Subpart ZZZZ monitoring, reporting, and recordkeeping requirements vary based on engine size, fuel firing type, and HAP classification of the facility (i.e., major or minor) and can include a combination of the following:
- Installation of a non-resettable hour meter on the engine.
- Depending on the specific emission limits that apply, the installation of a continuous emissions monitoring system (CEMS) or a continuous parametric monitoring system (CPMS) to demonstrate compliance with the applicable emission limits.
- Recording the duration of operation, maintenance activities, and engine testing.
- Submittal of initial notification of rule applicability.
- If a performance test is required for the engine, a notification of the intent to conduct the performance test.
- Submittal of a semiannual notification of compliance status report that provides an update on compliance with Subpart ZZZZ.
- Preparation of a startup, shutdown, and malfunction (SSM) plan that defines periods of startup, shutdown, and malfunction for the engine.
The ICE regulations described above can be easy to overlook, particularly when an emergency generator or fire pump is being installed as part of a larger air quality permitting project. Given that there are no engine size-based applicability thresholds associated with these rules, even the smallest engines can create compliance issues if the regulations are not properly identified, evaluated, and planned for. Each of the regulations is very complex in terms of varied requirements that depend on a number of engine- and facility-specific parameters (i.e., engine size, model year, etc.). It is critical that each generator be evaluated individually based on the appropriate engine parameters, and that fuel requirements for the engines are considered as they could impact fuel usage and delivery to other combustion sources at a facility. Knowledge of these regulations is particularly important for communications with engine suppliers, so that facilities can specifically confirm that an engine being purchased will comply with the appropriate emission limits. ALL4 has the experience to assist facilities with determining each rule’s applicability and understanding which requirements apply to affected engines.