EPA Administrator Carol Browner signed
a final rule establishing new emission standards for commercial marine diesel engines at or above 37 kW (approximately 50 hp). The final rule makes only minor modifications to EPA's December 1998 notice of proposed rulemaking (NPRM),
EPA's final rule aplies emission standards to new engines only, beginning with the 2004 model year. Vessels and engines built before 2004 will not be subject to emission control requirements. However, if a vessel is subsequently modified such that 50 percent of the modified vessel's value is derived from new material or components, the vessel will be considered new and will be required to meet engine emission standards in effect at the time the modifications are made.
EPA believes this will prevent companies from re-using parts from used vessels to avoid emission standards. EPA also retains the right to revisit the issue of applying emission standards to rebuilt or remanufactured engines, if - in the agency's opinion, industry does not take adequate steps to introduce new emission reducing technologies
EPA considers the ruling to be the second tier in a three-tier approach to commercial marine engine emisson standards. EPA considers the nitrogen oxide standards established by Annex VI to the International Convention for the Prevention of Pollution from Ships (MARPOL) to be the first tier of emission standards.
However, since MARPOL Annex VI has not yet been ratified, compliance with these standards will be encouraged, but not required.
The rulemaking represents the second tier. EPA has divided marine engines into three broad categories and a number of subcategories based on an engine's per-cylinder displacement.
For Category One engines (smaller engines derived from land-based, non-road engines) EPA will apply existing land-based, nonroad engine emission standards beginning with the 2004 model year. Emission standards for Category Two engines (larger engines derived from locomotive engines) will be based on EPA standards for locomotive engine emissions, but will be somewhat less stringent, due to technical problems associated with the wholesale application of these standards to marine engines.
Category three engines - used in large oceangoing vessels - are not found on tugboats or towboats.
EPA also envisions a third tier of engine emission standards, to be developed and proposed at a future date.