Exhaust emissions of three vehicles fueled with compressed natural gas (CNG) were compared with emissions of three counterpart gasoline vehicles. The natural gas vehicles were tested on four CNG fuels covering a wide range of pipeline natural gas compositions. The gasoline vehicles were tested on AQIRP Industry Average gasoline and a reformulated gasoline meeting California 1996 regulatory requirements.Nonmethane hydrocarbon (NMHC) and toxic air pollutant emissions of the CNG vehicles were about one-tenth those of their counterpart gasoline vehicles, while methane emissions were about ten times those of the gasoline vehicles. Carbon monoxide (CO) and nitrogen oxides (NOx) emissions were more variable among the three vehicle pairs. CO emissions ranged from 20 to 80% lower with CNG than with gasoline, and NOx ranged from 80% lower with CNG to equivalent to gasoline.Comparing the four CNG fuels, methane increased about 40%, NMHC decreased about 40%, and reactivity-weighted emissions decreased about 15% when CNG fuel methane content increased from 91 to 98% of fuel hydrocarbons (86 to 97% of total gas composition). There were no statistically significant effects on CO, NOx or toxic air pollutants.Fuel economy expressed as miles per million BTUs was about 20% lower for the CNG vehicles than for their gasoline counterparts. Reactivity-weighted emissions (RWE), calculated to estimate differences in potential ozone forming characteristics of emissions, were about 90% lower for the three CNG vehicles than for their gasoline counterparts when the calculation was based on NMHC emissions alone, and about 80% lower when exhaust methane and CO were included. The fuel effects on RWE parallel the effects on NMHC mass.Reformulated test gasoline C2 representing California Phase 2 gasoline, tested in the gasoline vehicles, had consistently lower NMHC, CO, and NOx and toxics emissions than AQIRP Industry Average gasoline. The average decreases in the three emissions were 24%, 21%, 12% and 36%, respectively. These results are consistent with other AQIRP data for these fuels.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Comparison of CNG and Gasoline Vehicle Exhaust Emissions: Mass and Composition - The Auto/Oil Air Quality Improvement Research Program


    Additional title:

    Sae Technical Papers



    Conference:

    1995 SAE International Fall Fuels and Lubricants Meeting and Exhibition ; 1995



    Publication date :

    1995-10-01




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




    Comparison of CNG and Gasoline Vehicle Exhaust Emissions: Mass and Composition - The Auto/Oil Air Quality Improvement Research Program

    Hochhauser, A. M. / Koehl, W. J. / Benson, J. D. et al. | British Library Conference Proceedings | 1995


    Effects of Gasoline Sulfur Level on Mass Exhaust Emissions - Auto/Oil Air Quality Improvement Research Program

    Hochhauser, Albert M. / Benson, Jack D. / Painter, Louis J. et al. | SAE Technical Papers | 1991



    Gasoline Reformulation and Vehicle Technology Effects on Emissions - Auto/Oil Air Quality Improvement Research Program

    Burns, V. R. / Rapp, L. A. / Koehl, W. J. et al. | British Library Conference Proceedings | 1995


    Gasoline Reformulation and Vehicle Technology Effects on Emissions - Auto/Oil Air Quality Improvement Research Program

    Hochhauser, Albert M. / Rippon, Brian / Benson, Jack D. et al. | SAE Technical Papers | 1995