The following are some of the important regulatory steps:
- On July 11, 2006, the EPA promulgated emission regulations for stationary diesel engines, which require that most new stationary diesel engines meet the Tier 1-4 emission standards for mobile nonroad engines.
- On January 18, 2008, EPA promulgated emission standards for stationary spark ignition (SI) internal combustion engines.
- On May 21, 2010, the EPA proposed amendments to the 2006 rule to strengthen the standards for engines of 10-30 liters per cylinder to levels required by marine engines of the same sizes. The proposed rule would also align emission standards for engines above 30 liters per cylinder with those for marine engines. The proposal also includes minor revisions to the SI engine requirements.
In addition to the NSPS standards, emission requirements for certain categories of new stationary engines are also specified by the National Emission Standards for Hazardous Air Pollutants (NESHAP). Since the NSPS and NESHAP emission standards were adopted through a number of rules—in some cases prompted by court actions against EPA by various environmental or industry groups—the structure of the regulations is complex. This article covers the NSPS standards for new diesel engines (SI engines are also regulated, but not covered by this summary). Also available is a summary of NESHAP requirements for existing stationary engines.Emission regulations for stationary diesel engines are published in Title 40 Chapter I, Part 60 of the Code of Federal Regulations (CFR).