Engine Guidance

Contact: See Below
Agency: Environment, Great Lakes, and Energy


animated illustration of a combustion engine with its pistons moving up and down

A stationary reciprocating internal combustion (IC) engine converts chemical energy to mechanical energy via the combustion of fuel and air. The process occurs inside a cylinder where the combustion of the mixture pushes a piston through the cylinder turning a crankshaft. Stationary reciprocating IC engines are nonroad, nonmobile engines that remain stationary at a single site for at least a full year. A stationary RICE can be categorized as either compression ignition (CI) or spark ignition (SI). CI engines normally fire diesel fuel oil, whereas SI engines primarily fire natural gas, landfill gas, or gasoline. Stationary reciprocating IC engines are commonly used to produce electricity and to power mechanical equipment such as pumps and compressors.

The combustion process of IC engines causes the emittance of air pollutants to the atmosphere through the exhaust. These air pollutants have an adverse impact on public health and the environment, especially for susceptible populations with respiratory and cardiovascular issues. Pollutants commonly emitted from stationary reciprocating (IC) engines include nitrogen oxides (NOx), carbon monoxide (CO), volatile organic compounds (VOCs), and particulate matter (PM), along with hazardous air pollutants (HAP) and toxic air contaminants (TAC) of formaldehyde, acetaldehyde, acrolein, methanol, and PAH. For these reasons, the emissions from stationary reciprocating (IC) engines are regulated by EGLE and the EPA.


If you are planning on installing, modifying, reconstructing, relocating, and/or operating a stationary RICE in Michigan, you may be required to have an air permit. Rule 201 of the Michigan Air Pollution Control Rules requires a person to obtain an approved Permit to Install (PTI) for any potential source of air pollution unless the source is exempt from the permitting process. Not all stationary RICE units will require an air permit. For example, if the engine meets the permit exemptions outlined in Rules 278 and 285(2)(g), the engine could be considered exempt from the need for a PTI. It is important to note that although your stationary RICE may be exempt from state air permitting, it still may be subject to the federal regulations listed below.

Information to have for permit applicability, application, and subject rules and regulations include the following:

  • type of source (major or area)
  • intended use (emergency, peak shaving, limited use, etc.)
  • engine manufacture, model, and year (new or existing)
  • date of installation
  • emission certification (if available)
  • engine design: power rating, displacement per cylinder, method of ignition (CI or SI), type of fuel used, fuel consumption rate, power stroke (two or four), air-to-fuel ratio (rich-burn or lean-burn), air pollution control equipment (if any)

Federal Regulations

The United States Environmental Protection Agency (USEPA) finalized standards that place requirements on the owners/operators as well as the manufacturers of stationary reciprocating internal combustion engines to minimize the release of HAPs and criteria pollutants. The federal New Source Performance Standards (NSPS), Subparts IIII and JJJJ regulate emissions of criteria pollutants from new, modified, and reconstructed stationary engines. The federal standard, referred to as the National Emissions Standard for Hazardous Air Pollutants (NESHAP), Subpart ZZZZ regulates HAP emissions from all existing, reconstructed, and new stationary engines. Subpart ZZZZ is complex since there are many previously unregulated smaller engines, including those designated for emergency use, that are now subject to federal regulations.


First, determine if your source is considered a major source or minor source of HAP emissions. A major source of HAP emissions has the potential to emit 10 tons per year (tpy) or more of any single HAP, or 25 tpy or more of combined HAPs.

Second, determine if you have a stationary compression ignition (CI) or spark ignition (SI) engine.

Third, consider the purpose of the engine. Is it an emergency or non-emergency engine? Is it a black-start or limited-use engine?

Fourth, verify the engine's site rating in brake horsepower (HP). You may also need to know the engine's displacement in liters per cylinder.

Fifth, determine if the engine is considered existing, new or reconstructed. For a major source with an engine site rating of over 500 HP, existing means the engine was installed or built on-site before December 19, 2002. New or reconstructed means the engine was installed or built on or after December 19, 2002. For a major or area source with an engine site rating under 500 HP, existing means the engine was installed or built on-site before June 12, 2006. New or reconstructed means the engine was installed or built on site or after June 12, 2006.

Once the above information is known, the following tools can be used to determine the federal NESHAP and NSPS requirements that are applicable to your engine.

Continuous Compliance

The air permit and subject federal regulations for your stationary RICE may contain recordkeeping, performance testing, and reporting requirements to make permit conditions and federal standards practically enforceable.

Monitoring and Recordkeeping

Typical recordkeeping requirements for engines include fuel usage, hours of operation (if emergency), oil analysis results, maintenance performed on engine and air pollution control equipment (if applicable), malfunctions that occurred with duration and actions performed following, and air pollution control equipment performance parameters (if applicable).

Performance Testing

Depending on the power output of the engine, the type of source, and the year it was constructed, the engine may be subject to performance testing to show compliance with established emission limits in a PTI or federal regulation. For example, an existing non-emergency Cl engine greater than 100 HP at a major source must have an initial emission performance test, and re-test every 8,760 hours of operation or three years for engines greater than 500 HP (five years if limited use).


The federal regulations have reporting requirements for a subject stationary RICE. These reports could include initial notification of compliance, notification of compliance after a performance test, along with semi-annual and annual compliance reports. The reports check to see if the source is in compliance with the subject emission limitations or operating limitations, or if there were deviations that occurred. A certification by a responsible official is required.

Annual Emissions Reporting

The federal Clean Air Act requires that each state maintain an inventory of air pollution emissions for certain facilities and update this inventory each year. Michigan's emission inventory is collected annually using the Michigan Air Emissions Reporting System (MAERS) and submitted to the USEPA to be added to the national data bank. Not all facilities are required to report their annual emissions. Facilities that are generally required to report are considered major sources, synthetic-minor sources, or subject to a federal NSPS, such as Subpart IIII or JJJJ.

Useful Tools

The following links can be useful for calculating potential to emit (PTE) and in the preparation of a PTI application for a stationary RICE.


For questions regarding permit applicability and subject regulations, please contact your district office or inspector.