Reciprocating Internal Combustion Engines (RICE)

RICE are common combustion sources that collectively can have a significant impact on air quality and public health. The air toxics emitted from stationary engines include formaldehyde, acrolein, acetaldehyde, and methanol. Exposure to these air toxics may produce a wide variety of health difficulties for people, including central nervous system problems and irritation of the eyes, skin, and mucous membranes. RICE engines also emit the conventional air pollutants created when fuel is burned, including carbon monoxide (CO), nitrogen oxides (NOx), volatile organic compounds (VOCs), and particulate matter (PM). The health effects of these pollutants include a range of respiratory issues, especially asthma, among children and seniors.

EPA air quality requirements for stationary engines differ according to:

• whether the engine is new or existing, and
• whether the engine is located at an area source or major source and whether the engine is a compression ignition or a spark ignition engine. Spark ignition engines are further subdivided by power cycle (i.e., two-stroke vs. four-stroke) and whether the engine is rich burn (burning with a higher amount of fuel as compared to air) or lean burn (less fuel compared to air).

EPA air quality requirements for stationary engines differ according to:

• Engines used at "area sources" of air toxics emissions and constructed or reconstructed before June 12, 2006
• Engines used at "major sources" of air toxics emissions, have a site rating of less than or equal to 500 hp, and constructed or reconstructed before June 12, 2006
• Engines used at "major sources" of air toxics for non-emergency purposes, have a site rating of greater than 500 hp, and constructed or reconstructed before December 19, 2002

Ruling Requirements:

The affected stationary diesel engines must comply with CO emission limits or must be fitted with emission controls, such as diesel oxidation catalysts, to reduce CO emissions by 70%.

The rule also requires the use of ultra-low sulfur diesel fuel for stationary non-emergency engines greater than 300 hp with a displacement of less than 30 liters per cylinder. The regulation will be fully implemented by 2013.

The regulation includes a number of other provisions, including work practices for engine operators. Stationary engines above 300 hp must also be equipped with closed or open crankcase filtration system in order to reduce metallic HAP emissions. While the regulation does not mandate the emission control technology, the EPA designed the standards based on the capabilities of the diesel oxidation catalyst (DOC).

The affected stationary diesel engines must comply with CO emission limits or must be fitted with emission controls, such as diesel oxidation catalysts, to reduce CO emissions by 70%.

The rule also requires the use of ultra-low sulfur diesel fuel for stationary non-emergency engines greater than 300 hp with a displacement of less than 30 liters per cylinder.

The regulation includes a number of other provisions, including work practices for engine operators. Stationary engines above 300 hp must also be equipped with closed or open crankcase filtration system in order to reduce metallic HAP emissions. While the regulation does not mandate the emission control technology, the EPA designed the standards based on the capabilities of the diesel oxidation catalyst.

Diesel oxidation catalysts are available and recommended by the EPA to meet the emission regulations. In addition, for engines greater than 500 HP, a continuous parametric monitoring system must be utilized to measure pressure drop across the catalyst, as the pressure drop across the catalyst must not change by more than 2 inches of water from the pressure drop across the catalyst that was measured during the initial performance test. In addition, temperature must be measured to ensure that the catalyst inlet temperature is between 450F and 1350F.

To determine the HAP requirements for your specific engine, you must know the following information: Horsepower, operating hours per year, and if you have an area or major source of emissions.

The EPA has provided an applicability flowchart to determine what category your engine falls under.

For non-emergency engines

• between 300 and 500 HP at either an area or major source:

  An initial performance test is required to demonstrate that emission standards are achieved using the oxidation catalyst.

• greater than 500 HP located at an area source:

  Testing depends on the use of your engine. For "Not limited use engines," you must perform an initial performance test and re-test every 8,760 hours of operation or 3 years, whichever comes first. You must also continuously monitor and record the catalyst inlet temperature, and perform monthly monitoring of the pressure drop across the catalyst. For "Limited use engines,” you must perform an initial performance test and re-test every 8,760 hours of operation or 5 years, whichever comes first. You must also continuously monitor and record the catalyst inlet temperature and perform monthly monitoring of the pressure drop across the catalyst.

• greater than 500 HP located at a major source:

  You must perform an initial performance test, and re-test every 8,760 hours of operation or 5 years, whichever comes first. You must also continuously monitor and record the catalyst inlet temperature and perform monthly monitoring of the pressure drop across the catalyst.

Catalyst inlet temperature on non-emergency CI RICE engines greater than 500 HP is required to be continuously monitored and recorded. Pressure drop across the catalyst must also be measured on a monthly basis. There are currently no specific performance requirements promulgated by the EPA for the monitoring system, but they are expected in the 40 CFR part 63, subpart ZZZZ ruling expected in August 2010.