Exhaust characteristics of Nitrous oxide from marine engine

Under Kyoto protocol, 37 countries (“Annex I countries”) commit themselves to reduce four greenhouse gases (GHG) (Carbon dioxide, Methane, Nitrous oxide, Sulphur Hexafluoride) and two groups of gases (Hydrofluorocarbons and Perfluorocarbons) produced by them. Nitrous oxide (N₂O) is one of the main four GHG and has strong global warming effect. Assuming 120-year period, it has 310 times more impact per unit weight than carbon dioxide (CO₂). There are some reports on the N₂O emission characteristics of stationary power plants and land transportation, but that of marine transportation is very limited. Therefore, in this study, the authors investigated the effects of engine operating conditions on N₂O emission characteristics of a training ship at sea and examined relationships between N₂O and the other gaseous emissions. Experimental results show that the emission characteristics of N₂O are related to exhaust gas temperatures and air excess ratios and are rather different from those of NO.