Last month the Environmental Protection Agency (EPA) announced that it is adopting emission standards for new marine diesel engines that will be installed on vessels flagged or registered in the U.S. While the new regulations apply mainly to large oceangoing ships, they are merely the first strike in a series of moves designed to reduce emissions from all marine vessels
The near-term, Tier 1 standards in this rule are equivalent to the internationally negotiated emission limits for oxides of nitrogen (NOx). These standards will go into effect in 2004 and are based on readily available emission-control technology. EPA also said that it would undertake another rulemaking in a few years to consider a second tier of more stringent standards.
The Tier 1 standards apply to marine diesel engines manufactured January 1, 2004 or later if they will be installed on vessels flagged or registered in the United States1. The Tier 1 standards will apply to older engines only if they are converted from land-based to marine engines or they are installed on a new vessel. This final rule applies to "new" marine diesel engines and to new marine vessels that include marine diesel engines. In general, a "new" marine diesel engine or a new marine vessel is one that is produced for sale in the United States or that is imported into the United States. The emission standards established in this final rule, therefore, will typically apply to marine diesel engines that are installed on vessels flagged or registered in the Unites States.
Marine diesel engines with per-cylinder displacement at or above 30 liters are also known as Category 3 marine diesel engines. They range in size from about 2,500 to 70,000 kW (3,000 to 100,000 hp). These are very large marine diesel engines used for propulsion power on ocean-going vessels such as container ships, oil tankers, bulk carriers, and cruise ships.
Marine diesel engines with per-cylinder displacement between 2.5 and 30 liters engines are also known as Category 1 and Category 2 marine diesel engines. They range in size from about 500 to 8,000 kW (700 to 11,000 h[). These engines are used to provide allow propulsion power on many kinds of vessels including tugboats, pushboats
, supply vessels, fishing vessels, and other commercial vessels
in and around U.S. ports. They are also used as stand-alone generators for auxiliary electrical power on many types of vessels. In 1999, EPA adopted emission standards for commercial marine diesel engines smaller than 30 liters per cylinder (Category 1 and Category 2). Under that program, the internationally negotiated NOx standards would be voluntary until EPA's more stringent Tier 2 standards begin to apply.
EPA's Tier 2 standards are more stringent than the MARPOL Annex VI2 NOx standards. EPA's Tier 2 standards also include limits for particulate matter, carbon monoxide, and hydrocarbon emissions. Information about these standards can be found in the EPA fact sheet entitled, "Emission Standards for New Commercial Marine Diesel Engines" (EPA420-F-99-043, November 1999) and on EPA's Web site at www.epa.gov/otaq/marine.htm.
What are the Limits?
The near-term Tier 1 standards are equivalent to the internationally negotiated NOx limits adopted by the IMO in MARPOL Annex VI. These Tier 1 standards will be enforceable on U.S. vessels with engines manufactured January 1, 2004 or later. These standards were voluntary for Category 1 and Category 2 marine diesel engines under our 1999 rule; they are now mandatory for those as well as Category 3 marine diesel engines. The NOx standard varies from 9.8 to 17 grams per kilowatt-hour (g/kW-hr), depending on an engine's maximum operating speed.
These near-term standards are achievable with less than one year of lead time because manufacturers are already certifying their engines to the equivalent international standards under our program for Voluntary Statements of Compliance. These near-term standards are being achieved through the application of currently available technology, including optimized turbocharging, higher compression ratios, and optimized fuel injection. Engines meeting the Tier 1 standards have emission levels about 20 percent lower than uncontrolled levels.
The Tier 1 standards will continue to apply to Category 3 marine diesel engines until we adopt more stringent standards in a future rulemaking.
The Tier 1 standards will continue to apply to Category 1 and Category 2 marine diesel engines until 2007, when the more stringent Tier 2 standards we adopted in 1999 go into effect. The international standards apply to engines installed on vessels constructed on or after January 1, 2000, but they are not yet enforceable.
This final rule commits EPA to adopt technology-forcing Tier 2 standards for Category 3 marine diesel engines by April 2007. EPA will consider the availability of advanced technologies such as those used in other diesel engine applications as well as water emulsification and selective catalytic reduction. Engine manufacturers are already developing ways to apply these technologies to marine diesel engines.
EPA is not adopting emission standards for particulate matter (PM) from Category 3 engines in this final rule. The majority of PM emissions from large marine diesel engines comes
directly from the high concentration of sulfur in the residual fuel they use, so the simplest way to reduce these emissions is by removing sulfur from the fuel. Annex VI provides a mechanism to control the sulfur content of fuels used by vessels that operate in specially designated SOx Emission Control Areas (SECAs).
After the Annex goes into force, ships operating in these designated areas must use marine fuel with a sulfur content below 15,000 ppm or aftertreatment technology to achieve equivalent emission reductions
(for comparison, sulfur levels in marine residual fuels may be as high as 45,000 ppm). EPA intends to investigate this special designation for one or more areas in the United States, and will also reconsider this issue in EPA's future rulemaking.