Ships powered with low-sulfur diesel fuels may have cleaner emissions and actually perform better than when powered with other diesel fuels, according to findings by Oak Ridge National Laboratory and the Navy. The goal of the joint study, which looked at two-stroke marine engines operating on five types of fuel, was to determine engine performance and emissions of particulate matter and nitrogen oxide. While marine diesels produce 14 percent and 16 percent of global nitrogen and sulfur oxides, respectively, the emissions are of even greater concern along coasts and ports in such cities as Los Angeles, San Francisco, Houston and Boston. Furthermore, the Environmental Protection Agency and others are now regulating emissions from marine sources, and complying with these new regulations will require low-sulfur fuel and emission control. The study showed that the low-sulfur fuels had no negative effect on engine efficiency and there was some improvement associated with Fisher-Tropsch fuel. Although no improvements in nitrogen oxide emissions were noted, the study showed that some alternative fuels reduced particulate matter by up to 50 percent. The research was funded by the Navy and DOE's Energy Efficiency and Renewable Energy State Partnerships Program.
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