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January 16, 2013
Air rule relaxed for emergency engines

Expansion of the number of hours an emergency engine can operate when participating in emergency demand response programs is a top item in EPA’s amended National Emissions Standards for Hazardous Air Pollutants (NESHAP) for stationary reciprocating internal combustion engines (RICEs).   The action amends two rules the Agency issued in 2010, both of which prompted petitions for reconsideration. 

According to the EPA, there are over 1 million RICEs in the United States.  In addition to RICE participation in emergency response programs, the amendments apply to engines used in sparsely populated areas for oil and gas production, engines in remote areas of Alaska, engines that are to be replaced in the next few years because of state and local requirements, certain engines installed in 2006, and engines for offshore vessels.

Level 2 alerts

The EPA issued rules in March and August 2010 covering existing compression ignition (CI) engines and spark ignition (SI) engines, respectively.  CI engines use diesel fuel while SI engines use mainly natural gas and gasoline fuels.  Under the rules, in an emergency, any engine of any size may operate without emissions limits.  But the time allowed for emergency demand response programs activated during Level 2 energy emergency alerts (EEAs) (i.e., when there is true potential for a blackout) was limited to 15 hours a year. 

Petitioners informed the Agency that the 15-hour limit would typically cover the hours for which an emergency engine is expected to be called upon, but would not be sufficient to allow engines to participate in emergency demand response programs.  Some regional transmission organizations and independent system operators require that engines be available for more than 15 hours.  For example, the emergency load response program of one operator requires that emergency engines be available for 60 hours per year to meet emergency demand response situations.

The EPA was sympathetic to the concern.  Accordingly, the final amendments specify that owners and operators can operate their engines as part of an emergency demand response program Level 2 EEA within the 100 hours already provided for operation for maintenance and testing

Populated/nonpopulated areas

Other amendments include:

  • Replacing numerical emissions limits for existing area source SI engines above 500 horsepower (hp) in populated areas with requirements to install catalytic controls, conduct an initial test and annual performance test checks of the catalyst, and equip the engine with a high temperature shutdown device or monitor the catalyst inlet temperature continuously
  • Specifying that existing area source stationary SI four-stroke engines above 500 hp that are not located in populated areas are subject to management standards
  • Allowing Tier 1 and Tier 2 certified stationary CI engines scheduled to be replaced due to state or local rules to meet management practices rather than emissions limits until January 1, 2015, or 12 years after installation date, but not later than June 1, 2018
  • Adding an option (i.e., a 30 percent reduction of total hydrocarbon emissions) for demonstrating compliance with the formaldehyde emissions limit
  • Specifying that existing area source stationary CI nonemergency engines above 300 hp on offshore drilling vessels are subject to management practices
  • Broadening the definition of remote areas of Alaska to allow wider use of the option to comply by conducting management practices rather than meeting emissions limits

The EPA has also revised the New Source Performance Standards (NSPS) for stationary internal combustion engines (ICEs) to ensure consistency with the RICE NESHAP.  In particular, the amendment specifies how the NSPS will apply to emergency engines used for demand response.

Click here for the final RICE amendments.

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