Possible Solutions for Reducing NOx and SOx Emissions from Large Cargo Ships

In an attempt to curb air pollution from the shipping industry, the U.S. Environmental Protection Agency (EPA) proposed two new sets of standards in July 2009, which requires ships that have compression-ignition engines with a capacity of 30 liters or more per cylinder in U.S. waters to cut nitrogen oxides (NOx) emissions by 15%-25% by 2011, and up to 80% by 2016 from the current level. The stringent new standards will force shipping operators to invest in more efficient and cleaner engine and emission reduction technologies. This paper summarized some potential solutions for emissions reduction from large cargo ships, e.g., selective catalytic reduction (SCR) for NOx reduction, blending of biofuel with heavy fuel oil (HFO), application of oxygenates in marine diesel, sea water scrubbing for SOx reduction, and plasma technology for emission reduction, etc.