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  • Josh Shkrab

Is Your Facility Exempt From The Reciprocating Internal Combustion Engines Rule?

Updated: Aug 29, 2023

The National Emission Standards for Hazardous Air Pollutants (NESHAP) for Reciprocating Internal Combustion Engines (RICE) regulations were finalized on Friday, August 20, 2010. The rule is designed to regulate unconventional and conventional air toxics emitted from stationary engines that include formaldehyde, acrolein, acetaldehyde, methanol, carbon monoxide (CO), nitrogen oxides (NOx), volatile organic compounds (VOCs), and particulate matter (PM), which are the product of fossil fuel combustion. The health effects from exposure to these air toxics may produce a wide variety of health effects for people including irritation of the eyes, skin, and mucous membranes, respiratory illnesses, and central nervous system problems.

There are a several changes that were made from the proposed rule, including the exemption of existing combustion engines that are located at residential, commercial, or institutional facilities. This means that institutions such as hospitals, which have emergency generators, are possibly exempt from this regulation. An important determining factor in this rule is whether the source is classified as an area source or a major source. According to the EPA, an area source is defined as having the potential to emit less than 10 tons annually of a single hazardous air pollutant (HAP) or less than 25 tons annually of any combination of HAP. A major source is any facility that has the potential to emit more than 10 tons annually of an individual HAP or more than 25 tons of any combination of HAPs. Most hospitals fall under the area source category, which have different regulatory implications.

There are also differences in the rule for NESHAP and New Source Performance Standards (NSPS). For the NESHAP regulations, existing emergency engines located at residential, institutional, or commercial area sources are not subject to this rule. The only stipulation is that the emergency engine must meet the definition outlined in 40 Code of Federal Regulations 63, Subpart ZZZZ. The majority of hospitals meet this requirement, and are not subject to this part of the regulation.

There are several exemptions for the NSPS portion of the RICE rule. It is also important to note that there are differences in how an emergency engine is defined. The engine can either be defined as a compression or spark ignition engine. As defined by EPA, a compression engine is one that uses diesel fuel and achieves combustion by compressing the fuel. Conversely, the spark ignition engine uses spark plugs to achieve combustion, and uses alternative fuel sources including natural gas, landfill gas, digester gas, propane, and liquefied petroleum gas (LPG).

Based on these definitions, a compression engine at an area source is subject to the NSPS RICE rule if it was constructed (ordered) after July 11, 2005, and manufactured after April 1, 2006 (July 1, 2006 for fire pump engines), or modified or reconstructed after July 11, 2005. If a hospital’s emergency engine was not constructed after this date, they are not subject to the regulations.

A similar exemption exists for the spark ignition engine for area sources, which excludes hospitals from regulation, if the engine was constructed (ordered) after June 12, 2006. The primary reason for the exclusion of emergency engines in area sources is because EPA found that existing stationary emergency engines located at residential, commercial, and institutional facilities that are area sources were not included in the original Urban Air Toxics Strategy inventory and were not included in the listing of urban area sources.

Additional information on these new rules and regulations can be found on the EPA’s website and in the federal register.



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