The proposed rulemaking is designed to reflect the IMO’s ECA standards and broader worldwide program. The rule adds two new tiers of NO_x standards and strengthens EPA’s existing diesel fuel program for these ships.

There are two types of diesel engines used on oceangoing vessels (OGV): main propulsion engines (Category 3 marine diesel engines with per-cylinder displacement at or above 30 liters); and auxiliary engines (typically ranging in size from small portable generators to locomotive-size engines with power of 4,000 kW or more). EPA’s proposed rulemaking affects the Category 3 engines.

Current Clean Air Act (CAA) standards (Tier 1) for new Category 3 compression-ignition marine engines (marine diesel) at or above 30 liters per cylinder displacement have been in effect since January 2004 and are equivalent to the current international standards for marine engines contained in MARPOL Annex VI (which went into effect in 1997). These standards rely on engine based technologies to reduce exhaust emissions of nitrogen oxides (NO_x). MARPOL Annex VI was recently amended to add new tiers of engine NO_x emission standards and fuel sulfur limits.

EPA is proposing to revise the CAA engine program to include two additional tiers of NO_x standards for new Category 3 marine diesel engines installed on vessels flagged or registered in the United States.

• The proposed near-term Tier 2 standards for newly built engines would apply beginning in 2011 and would require more efficient use of current engine technologies, including engine timing, engine cooling, and advanced computer controls. The Tier 2 standards would result in a 15 to 25% NO_x reduction below the current Tier 1 levels.

• The proposed long-term Tier 3 standards would apply beginning in 2016 and would require the use of high efficiency after treatment technology such as selective catalytic reduction to achieve NO_x reductions 80% below the current levels.

• In addition to the NO_x emission limits, EPA is proposing standards for emissions of HC and CO from new Category 3 engines. EPA is not proposing to set a standard for PM emissions for Category 3 engines. However, significant PM emissions benefits will be achieved through the ECA fuel sulfur requirements that will apply to ships that operate in areas that affect US air quality. EPA is also proposing to require engine manufacturers to measure and report PM emissions.

EPA is also proposing a change to the diesel fuel program that would forbid the production and sale of marine fuel oil above 1,000 ppm sulfur for use in the waters within a US ECA and internal US waters, and allow for the production and sale of 1,000 ppm sulfur fuel for use in Category 3 marine vessels.

Air pollution from large ships, such as oil tankers and cargo ships, is expected to grow rapidly in line with port traffic increases. By 2030, the combined domestic and international strategy is expected to reduce annual emissions of nitrogen oxides (NO_x) from large marine diesel engines by about 1.2 million tons and particulate matter (PM) emissions by about 143,000 tons. When fully implemented, the coordinated effort would reduce NO_x emissions by 80% and PM emissions by 85% compared to current emissions.

The emission reductions from the proposed strategy would yield significant health and welfare benefits that would span beyond US ports and coastlines, reaching inland areas. EPA estimates that in 2030, this effort would prevent between 13,000 and 33,000 premature deaths, 1.5 million work days lost, and 10 million minor restricted-activity days. The estimated annual health benefits in 2030 as a result of reduced air pollution are valued between $110 and $280 billion at an annual projected cost of approximately $3.1 billion—as high as a 90-to-1 benefit-to-cost ratio, according to the agency.

EPA will begin accepting public comments on the proposed rulemaking. Additionally, EPA will hold public hearings on 4 August 2009 in New York, NY and 6 August 2009 in Long Beach, CA, at which additional comments will be accepted.

Resources

• EPA Oceangoing Vessels