Understanding and Complying with RICE Regulations

Issue 6 and Volume 119.


Stationary reciprocating internal combustion engines (RICE) are a valuable part of the American landscape. Across the country, there are an estimated 37,000 RICEs in a variety of sizes, ages, and fuel options performing work from emergency power generation to pumping fire water in remote areas.

Unfortunately, having one of these useful devices also means living with regulatory obligations under a complex web of requirements known as the RICE rules. Many RICE operators were not subject to air regulations before these rules were implemented. As such, they are new to the process and to the logic of compliance issues. This can all be a bit overwhelming. The RICE rules have many narrow specialized provisions, so they are a difficult place to begin. However, with patience and an organized systems approach, they can be successfully navigated.

RICEs are regulated because their combustion exhaust gas contains substances that have been designated as hazardous air pollutants (HAP). These emissions mainly consist of formaldehyde, acrolein, methanol, and acetaldehyde, but dozens of other organics, metals, and “criteria pollutants” can be produced depending on the type of fuel that is burned. Some of these compounds have acute or chronic effects and can irritate or corrode eyes, noses, throats, and lungs. They can also depress central nervous system function and are probable human carcinogens. RICE rules exist for a worthwhile reason-to control these emissions. The Environmental Protection Agency (EPA) has been working to regulate stationary internal combustion engines for over 12 years. The first proposed RICE National Emission Standards for Hazardous Air Pollutants (NESHAP) was published in 2002. These regulations specify Maximum Achievable Control Technology (MACT) and are sometimes called RICE MACT rules. Later, New Source Performance Standards (NSPS) for Stationary Compression Ignition (CI) and Spark Ignition (SI) Internal Combustion Engines were added.

Some RICEs, like this Wartsila engine at a power plant in Pearsall, Texas, are very clearly stationary and covered under specific regulations. Operators should be careful though; even engines mounted on mobile platforms like skids are considered stationary if they remain at a single site for at least a full year or season. Image Courtesy: Wartsila
Some RICEs, like this Wartsila engine at a power plant in Pearsall, Texas, are very clearly stationary and covered under specific regulations. Operators should be careful though; even engines mounted on mobile platforms like skids are considered stationary if they remain at a single site for at least a full year or season. Image Courtesy: Wartsila

All three rules have been amended multiple times. Staying current is challenging, but it is the foundation for successful compliance. Operators of RICEs should read regulations, or at least the summaries of those regulations on agency websites.

The rules include many special twists with narrow applications and are not discussed in detail here. Instead, this article reviews the key steps for a systematic approach to understanding and complying with these requirements, including:

  • Deciding whether RICE units are covered by regulations
  • Obtaining and understanding permits for covered RICE units
  • Complying with permits (including what to do if some requirements have been missed)


RICE operators should carefully examine regulations to assess which RICEs are considered “stationary.” Even engines mounted on mobile platforms such as skids are considered stationary if they stay at a single site for at least a full year or season.

Information about each engine should be compiled into a master list that includes:

  • Serial numbers
  • Engine types
  • Fuel (particularly if landfill or digester gas is used)
  • Date of manufacture or modification/reconstruction
  • Size (brake horsepower or horsepower)

The application of regulations to a specific RICE also depends on answers to several questions concerning that RICE’s status:

Is the RICE a “major source” or an “area source”?

Major sources of HAP are those that have the potential to emit greater than 10 tons per year (tons/yr) of any single HAP, or 25 tons/yr of any combination of HAPs. Potential to Emit is defined as the maximum emissions based on physical and operational design, not necessarily the actual annual emissions. It is calculated based on emission factors from the engine manufacturer or the EPA’s AP-42. However, reductions in a RICE’s emission potential due to pollution control equipment, restrictions on operating hours, or restrictions on fuel type can be considered in the calculations if those reductions are federally enforceable (written into the permit or regulation). For example, the operating year for emergency RICE units is by definition limited to 100 hours. Many operators choose to accept limits so that a source will be classified as “area” rather than “major”.

Is the RICE “existing” or “new”?

A RICE’s status as existing or new depends on the date on which the facility began “a continuous program of construction or reconstruction”, or the date it entered into a contractual obligation for on-site installation or reconstruction of the engine.

If the size of the engine is greater than 500 horsepower (HP), and the engine is located at a major source, the threshold date is December 19, 2002. These engines are considered to be “existing” if they were installed or contracted before this date, and are considered to be “new” if installed after this date.

For engines greater than 500 HP at major sources, and all engines at area sources, the date of demarcation is June 12, 2006.

Owners and operators should be especially aware when modification or reconstruction of the engine would cause it to be considered “new.”

Stationary RICEs, such as this fully remote controlled Guascor SFGLD 480 gen-set provided by Dresser-Rand to Storms Hog Farm, can be classified by fuel type, size, end use, and many other variables, many of which affect the rules that regulate them. Image Courtesy: Dresser-Rand
Stationary RICEs, such as this fully remote controlled Guascor SFGLD 480 gen-set provided by Dresser-Rand to Storms Hog Farm, can be classified by fuel type, size, end use, and many other variables, many of which affect the rules that regulate them. Image Courtesy: Dresser-Rand

Is the RICE for “emergency” use?

Emergency RICEs must meet strict operating requirements or be subject to full standards including emission limits, which could necessitate expensive retrofits for existing engines. While there is no time limit on the use of the engine in emergency situations, emergency engines may only be used for up to 100 hours per calendar year of non-emergency use, including any combination of:

  • Maintenance checks
  • Readiness testing
  • Emergency demand response situations
  • Up to 50 hours per calendar year non-emergency and local reliability

The allowable non-emergency uses, particularly “emergency demand response” and “local reliability”, are tightly defined in the regulations. Emergency RICE owners and operators must ensure that any non-emergency uses are allowable and do not exceed time limits.

Applicability Tools

Once an engine’s data and status are known, an analysis is necessary to determine what specific requirements apply to the engine. Two useful tools facilitate this process; both are located on the EPA’s website:


The RICE rules themselves do not require permits; they simply set requirements for emission limits and operating conditions for covered engines. The EPA delegates permit-issuing authority to those states and local air pollution agencies whose programs are at least as stringent as federal requirements. This means that permitting agencies may have more or tighter requirements than the EPA does. Owners should check the local agency website to verify requirements, forms, and other details of their RICE program. Some agencies have standardized General Permits or Permit by Rule (PBR) templates that greatly streamline the permitting process.

Usually, the permitting process begins with a Permit to Install (PTI) or Construction Permit , followed by a Permit to Operate (PTO), which is granted after testing the source and showing that it meets the limits in the PTI. Some states grant a permit to install and operate (PTIO), which combines construction and ongoing requirements. In general, construction should not begin until a PTI or PTIO is obtained. Some states allow site-clearing or other prep work to proceed. Air permits can take up to a year to obtain, and simply preparing the application can take many months. In states with PBR or General Permit programs, permits can be granted in a matter of days if the source RICE meets program definitions

Permitting for major sources is more complex than for area sources, particularly if the facility is located in a non-attainment area. Situations such as these may require air quality modeling, consideration of offsets, MACT determinations, or other special activities. If a RICE is located at a facility that already has a Title V or other air permit, the permitting agency will address it as a permit modification. Often the agency will conduct a facility inspection during the permitting process. Permits typically expire after five to 10 years, depending on the state program. Generally, a renewal application is due six months prior to the expiration date.


Owners should read the permit carefully. If it references regulations, read those regulations to determine what they require. Do not gloss over these “boilerplate” references; they are enforceable provisions. Make a list of every action the permit requires. Most facilities have multiple types of RICE units that will have different requirements.

Emission Standards

Different emissions standards apply depending on the type, size, location, fuel, and use of each RICE unit. Compliance deadlines have already passed. Now, new and reconstructed engines must comply at startup. For example, engine manufacturers must certify 2007 model year (and later) engines with a displacement less than 30 liters per cylinder.

Existing RICEs were required to retrofit to reduce carbon monoxide (CO) emissions by 70 percent. Depending on the engine type, this was typically accomplished by oxidation catalyst (for lean burn diesel and natural gas engines), three-way catalyst (for rich burn natural gas engines), closed crankcase ventilation (CCV) systems, and/or diesel particulate filters.

Under the 2013 amendments, if CI engines are certified as Tier 1 or Tier 2, and are scheduled to be replaced due to state or local rules, they can meet management practices rather than emissions limits until 12 years after their installation date, but not later than June 1, 2018. Tier 3 certified CI engines installed before June 12, 2006 are considered in compliance with the NESHAP.

Performance Testing

Rather than requiring testing for all the HAPs of concern, EPA regulated formaldehyde and determined that CO could be tested as the surrogate to demonstrate that emission standards are achieved. The 2013 amendments allow four-stroke, rich-burn engines to test for the less expensive parameter of Total Hydrocarbons (THC).

Frequency of testing depends on the size and location of the engine. Major source non-emergency engines greater than 500 HP must have an initial performance test, and re-test every 8,760 hours of operation or five years, whichever comes first. Area source non-emergency engines greater than 500 HP must have an initial performance test, and re-test depending on operating hours. Those that operate greater than 100 hrs/yr must test every 8,760 hours of operation or three years, whichever comes first. Those that operate less than 100 hr/yr must test every 8,760 hours of operation or five years, whichever comes first. Non-emergency engines between 300 and 500 HP at either an area or major source must have an initial performance test, but do not require retesting.

Engines greater than 500 HP must also have a Continuous Parametric Monitoring System (CPMS) to assess temperature and pressure drops at the catalyst bed. The CPMS must be checked as part of the performance tests. The CPMS conditions that result in a successful performance test will become part of the ongoing operating requirements. A site-specific monitoring plan must be developed and implemented, including maintenance protocols for the CPMS.

For all performance tests, a Notification of Performance Test must be submitted at least 60 days in advance of the test date. The local agency or EPA region may require that the test protocol be submitted with this notification. Agencies may come and observe the test. Testing must be conducted in accordance with EPA methods. Reputable testing firms will know these requirements. Within 60 days after the test, results must be submitted to the agency. The report must demonstrate the ways in which all requirements of the test method were met (calibrations, analysis QA/QC, etc.).

Emergency Engine Runtime Limits

Emergency engines are not subject to emission controls. Instead, they have runtime limitations. Non-resettable hour meters are required for tracking use of emergency engines, and physical or electronic records must be kept. This data is very important. Without proof that the runtime limits are met, the RICE could be considered non-emergency and subject to the emission control requirements.

Maintenance Requirements

Engines must be operated and maintained according to their manufacturer’s written instructions. Operators must develop and implement a maintenance plan that addresses oil changes, air cleaners, spark plugs, hoses, and belts.

Start-up, Shutdown, and Malfunction

During the burn-in period (the first 200 operating hours) for a new, reconstructed, or rebuilt stationary RICE, deviations from emission or operating limitations are allowed. Engine idling at startup must be minimized to the period needed for appropriate and safe loading of the engine, not to exceed 30 minutes. Aside from these times, all emission standards apply, and any failure to meet them is considered a deviation.


Records must be kept for five years following the date of a given activity. These records are the evidence that requirements have been met. If actions are not documented, they cannot be proven.

Records should be kept for:

  • All correspondence with the agency
  • Engine maintenance
  • Oil analysis results
  • Hours of operation for emergency engines
  • Maintenance performed on operating, air pollution control, and CPMS equipment
  • CEMS Data
  • Occurrences and durations of malfunctions
  • Actions taken during these malfunctions
  • Daily fuel use (if using landfill or digester gas for 10 percent or more of the gross heat input annually)


There are three main types of reports:

  • Initial notifications. (New RICE notifications are due at startup.)
  • Semi-annual reporting for RICEs operated greater than 100 hr/yr.
  • Annual reporting for RICEs operated less than 100 hr/yr. (Starting in 2015, engines greater than 100 HP, which operate or commit to operate between 15 and 100 hours per year for emergency demand response need to submit an annual report .

All reports must be submitted using the EPA’s Central Data Exchange.


Occasionally, incidences of non-compliance may occur. Ongoing mistakes must be reported as deviations in the semi-annual report. Agencies are (perhaps unfortunately) accustomed to receiving deviation reports, but beware that these are self-reports of noncompliance. Enforcement actions can be taken by the state or local agency, the EPA, or citizens. EPA fines can be up to $37,500 per violation per day, but federal corporate sentencing guidelines allow for reduction of penalties if certain conditions are met. Supplemental Environmental Projects (SEP) are also commonly used to reduce penalties.

If an operator becomes aware that multiple or serious non-compliances have occurred, such as failing to submit an initial notification, it is wise to contact an attorney before submitting the deviation report or otherwise discussing the non-compliance with the agency. Do not try to hide a non-compliance issue once it has been discovered. It is better to self-report and correct the situation than to risk having the agency discover it.

Pathways through the RICE regulatory maze do exist. With a little planning, it is possible to organize and systematically meet compliance obligations.


Dr. Carol Clinton is president of E3 Strategic Partners, a WBE-certified firm specializing in EHS compliance and training, GHG modeling, and LEED/sustainability planning.