New Technology for a Changing Environment

Environmental concerns about pollution within cities and towns have prompted transit operators to investigate alternative fuel options for their buses. Although changes in emission control have taken place, gasoline and diesel fuel still produce pollutants that form a haze over our cities. A variety of alternative fuels have been suggested; two have been proven through widespread use - Liquefied Petroleum Gas commonly referred to as propane and Compressed Natural Gas (CNG).

Propane gas is the world's most widely used alternative fuel-nearly 4 million vehicles worldwide are running on propane. Propane-fueled vehicles emit significantly lower levels of carbon monoxide (93% below the standard), hydrocarbons (37% below the current standard), and nitrogen oxides (57% below the standard) than gasoline-fueled vehicles. Level of air toxin emissions from propane-fueled vehicles is also low.
-Alternative Fuels Data Center

Natural gas has an ignition temperature of about 1200 degrees Fahrenheit-about 600 degrees higher than gasoline. CNG is flammable only in concentrations from 5.3 to 15% in air, so if leaked is less likely to ignite than gasoline. In terms of fire, CNG vehicles may be considered safer than gasoline vehicles. Natural gas is not toxic or corrosive and will not contaminate ground water. Natural gas combustion produces no significant aldehydes or other air toxins.
-NC Division of Air Quality