12 May 2004

The US Environmental Protection Agency (EPA) has issued an Advance Notice of Proposed Rulemaking (ANPRM) which covers plans for future, more stringent emission standards for locomotive and marine diesel engines. The ANPRM was published together with the final Tier 4 rule for nonroad diesel engines. The Tier 4 regulation did not introduce emission standards for locomotive or marine engines. However, it did include a low sulfur diesel fuel provisions applicable to locomotive and marine fuels.

The EPA is considering more stringent standards for new and existing locomotives, as well as for new marine diesel engines with per cylinder displacement below 30 liters. The marine standards would apply to diesel engines used in all applications: commercial (excluding ocean vessels), recreational, and auxiliary. They would also apply to engines at or below 37 kW, which were previously included in the nonroad standards.

The emission standards would be modeled after the 2007/2010 highway engine program and the Tier 4 nonroad rule, with an emphasis on achieving large reductions in PM emissions through the use of advanced emission control technology. These standards would be based on the application of catalytic aftertreatment enabled by the availability of ultra low sulfur diesel fuel. The Tier 4 diesel fuel program has set a 15 ppm sulfur limit for locomotive and marine diesel fuel beginning in 2012.

For locomotive engines, built as early as 2011, the EPA considers establishing Tier 3 standards based on aftertreatment technologies for both PM (particulate filters) and NOx (NOx adsorbers, urea-SCR) emissions. Emissions for both pollutants would be reduced by about 90% relative to the engine-out levels. The locomotive Tier 3 NOx requirements would be phased-in within 3 years (i.e., by 2013).

A similar approach is considered for marine engines (with the exception of the largest engines Category 3, over 30 liters per cylinder). The PM controls could be introduced starting in 2011, with NOx standards phased-in over 3 years. Contrary to locomotives, the marine standards would apply only to new engines. Additional issues are present in Category 2 (5 - 30 liters per cylinder) marine engines using residual fuels of high sulfur content, which may be prohibitive for the use of such technologies as catalytic particulate filters. The final Tier 4 limits on sulfur content of marine diesel fuel do not apply to heavy oils (T90 > 700°F) used in Category 2 and Category 3 marine engines.

In addition to new engine standards, EPA is soliciting input on voluntary provisions that could encourage cleaner engines and retrofits, or accelerate replacement of existing engines.

Comments on the ANPRM will be accepted for 60 days from the date of Federal Register publication. The EPA expects to publish a Notice of Proposed Rulemaking for the rule by mid-2005 and a Final Rule by mid-2006.

Locomotive and marine engines ANPRM

Source: US EPA