ABSTRACT
In China, most of the studies of vehicular greenhouse gas (GHG) emissions have been focused on CO2 emissions. The investigation of non-CO2 GHGs, e.g. CH4 and N2O, are mainly carried out based on models developed in Europe and the US, and there are few vehicle emission tests for CH4 and N2O. In this study, 22 light-duty gasoline vehicles (LDGVs) were selected for tailpipe CH4 and N2O tests using chassis dynamometer, and their emission factors were obtained based on the NEDC driving cycle. The results showed that the CH4 emission factors of China I to China IV LDGVs were 0.048 g x km(-1), 0.048 g x km(-1), 0.038 g x km(-1) and 0.028 g x km(-1), respectively. For N2O, the emission factors of China I to China IV were 0.045 g x km(-1), 0.039 g x km(-1), 0.026 g x km(-1) and 0.021 g x km(-1), respectively. In the GHGs emissions (in terms of CO2 Eq.) per LDGV, the percentage of CH4 and N2O emissions decreased gradually with tightening of emission standards. The contribution of CH4 emissions was lower than 0.5% in the total emissions, and N2O share rate was between 3.03% and 6.35%. Therefore, tightening emission standards can effectively reduce the CH4 and N2O emissions, to mitigate the greenhouse effects caused by vehicle emissions.
