Technical Evaluation and Assessment of CNG/LPG Bi-Fuel and Flex-Fuel Vehicle Viability

    Research output: NRELTechnical Report


    This report compares vehicles using compressed natural gas (CNG), liquefied petroleum gas (LPG), and combinations of the two in bi-fuel or flex-fuel configurations. Evidence shows that environmental and energy advantages can be gained by replacing two-fuel CNG/gasoline vehicles with two-fuel or flex-fuel CNG/LPG vehicles. For two-fuel systems to be economically competitive, it is necessary todevelop a universal CNG/LPG pressure-regulator-injector and engine control module to switch from one tank to the other. For flex-fuel CNG/LPG designs, appropriate composition sensors, refueling pumps, fuel tanks, and vaporizers are necessary.
    Original languageAmerican English
    Number of pages66
    StatePublished - 1994

    Bibliographical note

    Work performed by J. E. Sinor Consultants, Inc., Niwot, Colorado

    NREL Publication Number

    • NREL/TP-425-6544


    • bi-fuel vehicles
    • compressed natural gas (CNG)
    • flex-fuel vehicles
    • liquefied petroleum gas (LPG)


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