Under a new federal rule effective September 6, 2016, owners and operators of stationary diesel engines—formally compression ignition internal combustion engines (CI ICEs)—may, in an emergency, temporarily override systems in those engines intended to force the use of emissions control devices.
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The rule amends EPA’s 2006 New Source Performance Standards (NSPS) for CI ICEs, which established limits on emissions of particulate matter, car nitrogen oxides (NOx), carbon monoxide (CO), and nonmethane hydrocarbons. The CI ICE NSPSs are generally modeled after EPA’s standards for nonroad and marine diesel engines and have been phased in with increasing stringency in four tiers beginning in 1996. Currently, Tier 4 NSPSs are in effect, but the new rule allows the operation of stationary CI ICEs under the Tier 1 standards during emergencies.