Abstract:
Emission Factor (EF) study is empirical functional relations between CO2 and CH4 for typical vehicles in Thailand from 4 different types of vehicles including heavy duty diesel vehicle (HDDV), light duty diesel vehicle (LDDV), light duty gasoline vehicle (LDGV), and motorcycle (MC). The relationships of both speed and different fuel types (diesel, gasoline, gasohol, liquid petroleum gas, and natural gas for vehicles) and speeds were also tested and developed to enable an estimation of greenhouse gas emission from a transport sector in Thailand. The emission levels of CO2 and CH4 in relation to Bangkok driving cycle were determined using a chassis dynamometer at the Automotive Emission Laboratory of the Pollution Control Department. Statistical analysis results clearly indicated the significant differences in EF-CO2 from different types of vehicles (p<0.05). The highest EF-CO2 with the range of 1,080.3-1,280.9 g/km was found in HDDV. Meanwhile, ranges of EF-CO2 from LDDV, LDGV, and MC were 231.9-338.1, 157.4-179.9, and 38.2-76.5 g/km, respectively. When concentrating on the EF-CO2 from vehicles using different types of fuels, HDDV with NGV as the fuel emitted higher average CO2 concentration than the HDDV with diesel fuel. In the case of LDDV, it was found that using diesel as fuel would emit higher average CO2 levels than the use of NGV. While LDGV with gasohol 91 was monitoring higher average CO2 levels, those LDGV types emitted with gasohol E20, LPG as well as NGV. In terms of MC at all speeds tested, MC with gasohol 95 emitted higher average CO2 concentrations than MC with either gasoline 91 and gasohol 91. Regarding to EF-CH4 from three types of vehicles (HDDV, LDDV, and LDGV) with NGV as a fuel source, average CH4 levels exhausted from those vehicles were 7.22, 0.82, and 0.17 g/km, respectively. In addition, it was found that LDGV was the type of vehicle with the highest average CH4:CO2 emission ratio (0.25). This LDGV which is usually used as a taxi car generally had accumulated running distances than other types of vehicles tested. The values of EF-CH4 and equivalent CO2 emission from this LDGV were 1.3 g/km and 13.8 ton/year/vehicle. When compare the levels of GHG emission from this current study to those levels reported by US.EPA and IPCC, higher and lower levels, respectively, were found. Furthermore, a study on a relationship between volumes of vehicles and fuel consumption indicated a linear relationship among EF, fuel consumption, numbers of vehicles, and vehicles kilometer travels. The higher levels of those 3 factors could contribute to the greater GHG emission. Finally, the GHG emission transport model can be used to estimate GHG emission from the development of traffic transport projects and made the decision for most benefit implementation. Results obtained from this present study can be applied and used as a database for an efficient GHG emission control and management for the transport sector in Thailand.