We apply the Waterway Network Ship Traffic, Energy and Environment Model (STEEM) to evaluate cost-effectiveness of three control strategies for reducing SO2 emissions from ships calling on West Coast U.S. ports, a potential SOx Emission Control Area (SECA) under international maritime regulations. Ships carrying U.S. foreign commerce emitted ~88,000 tons of SO2 in the U.S. West Coast EEZ in 2002. Compared to regulations prescribing low-sulfur fuels, a performance-based policy can reduce 70% more SO2 with savings up to $247 million per year for the West Coast fleet. Variation among marginal costs of control for individual ships choosing between fuel-switching and aftertreatment reveals strong cost-saving potential of an economic incentive instrument. Least-cost SO2 control for 4,748 unique ships traveling in existing European or hypothetical West Coast control areas shows that SECA emissions control targets can be achieved by scrubbing exhaust gas of only one out of ten ships, and annually saves up to $154 million beyond the performance-based control policy. Spatial evaluation of ship emissions reductions shows that market-based instruments can reduce more SO2 closer to land while being more cost-effective for the fleet. Results suggest that combining performance requirements with market-based instruments can control most effectively SO2 emissions from ships.

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Document Type


Department, Program, or Center

Sustainability (GIS)


RIT – Main Campus