11 May 1998

The US EPA published an Advance Notice of Proposed Rulemaking (ANPRM) to control emissions of oxides of nitrogen (NOx) and particulate matter (PM) from new diesel marine engines above 37 kW. These engines are used for propulsion and auxiliary power on both commercial and recreational vessels in a variety of marine applications.

This ANPRM supplements an earlier proposal for these engines initiated as part of an overall control strategy for new gasoline spark-ignition (SI) and diesel compression-ignition (CI) marine engines. This new program contains three sets of standards. First, for those marine diesel engines that are derived from or use land-based nonroad or highway engine technologies, EPA is contemplating an emission control program for diesel marine engines similar to the Tier 2 program proposed for nonroad land-based engines. Second, for engines that are derived from or use locomotive technologies, EPA is contemplating numerical emission limits similar to those applicable to land-based locomotives (finalized 17 December 1997) or those contained in Annex VI of the International Convention for the Prevention of Pollution from Ships (MARPOL 73/ 78). Third, for low-speed, high-horsepower engines used to propel ocean-going vessels, EPA is contemplating numerical emission limits adopted by the International Maritime Organization (IMO). The certification and compliance provisions being considered are also derived from the program for land-based nonroad diesel engines, but will reflect relevant differences in locomotive-size and larger marine engines that are used domestically.

If the standards and other requirements are implemented as proposed, the resulting emission reductions would translate into significant, long-term improvements in air quality in many areas of the US, particularly in port cities and coastal areas. Application of emission controls similar to the proposed nonroad Tier 2 standards are expected to result in NOx and PM reductions comparable to those expected from land-based engines, on a per-engine basis. The MARPOL Annex VI emission limits were intended to result in a 30% reduction of NOx emissions; actual emission reductions will depend on the age and other characteristics of the national fleet. Overall, the program would provide much-needed assistance to states facing ozone and particulate air quality problems that are causing a range of adverse health effects for their citizens, especially in terms of respiratory impairment and related illnesses.

Contact: Alan Stout, 734-214-4805, stout.alan@epamail.epa.gov

Source: US EPA