Bi-Fuel And Cng Vehicles

A bi-fuel vehicle has two separate fuel systems, one for gasoline or diesel and another for either liquefied propane gas (LPG) or compressed naturalgas (CNG). Because CNG and LPG stored in pressurized tanks, they cannot be simply pumped into the gasoline tank. The bi-fuel design allows the use of an alternative fuel when available.

The need for two separate fuel systems and a storage tank for a gaseous fuel increases the cost of bi-fuel vehicles and reduces cargo space. A propane tank, for example, is about the size of a spare tire.

Where low cost CNG or LPG is available, however, bi-fuel vehicles can offer a cleaner, more economical alternative to gasoline or diesel. CNG is one of the cleanest of the fossil fuels. Compared to gasoline, its use could bring about a significant reduction in tailpipe emissions of carbon monoxide (about 70%), nitrogen oxides (about 50%), and ozone-causing pollutants (about 90%). In addition, particulate emissions would be almost eliminated. In tests conducted in California, propane-powered vehicles produced about 45% less carbon monoxide than did gasoline vehicles and about 20% less nitrogen oxides; they also had about 60% less smog forming pollution.