title: Emission factors of air pollutants from CNG-gasoline bi-fuel vehicles: Part I. Black carbon.
abstract: Compressed natural gas (CNG) is considered to be a "cleaner" fuel compared to other fossil fuels. Therefore, it is used as an alternative fuel in motor vehicles to reduce emissions of air pollutants in transportation. To quantify "how clean" burning CNG is compared to burning gasoline, quantification of pollutant emissions under the same driving conditions for motor vehicles with different fuels is needed. In this study, a fleet of bi-fuel vehicles was selected to measure the emissions of black carbon (BC), carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) for driving in CNG mode and gasoline mode respectively under the same set of constant speeds and accelerations. Comparison of emission factors (EFs) for the vehicles burning CNG and gasoline are discussed. This part of the paper series reports BC EFs for bi-fuel vehicles driving on the real road, which were measured using an in situ method. Our results show that burning CNG will lead to 54%-83% reduction in BC emissions per kilometer, depending on actual driving conditions. These comparisons show that CNG is a cleaner fuel than gasoline for motor vehicles in terms of BC emissions and provide a viable option for reducing BC emissions cause by transportation.
authors.affiliation: Key Laboratory for Urban Habitat Environmental Science and Technology, Peking University Shenzhen Graduate School, Shenzhen, China; Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, Canada.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Xing
authors.affiliation: Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, Canada. Electronic address: kddu@ucalgary.ca.
authors.forename: Ke
authors.initials: K
authors.lastname: Du
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002681:China; D004784:Environmental Monitoring; D005742:Gasoline / Q000032:analysis*; D059206:Natural Gas / Q000032:analysis*; D053260:Soot / Q000032:analysis*; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D005742:Gasoline; D059206:Natural Gas; D053260:Soot; D001335:Vehicle Emissions
keywords: Bi-fuel vehicle; Black carbon; CNG; Emission factors; Motor vehicle pollutants