Emissions Performance of In-Use Alternative Fuel Vehicles

Interest in alternative fuels increased during the energy shortages of the mid-1970's and has continued due to the perceived potential environmental benefits of these fuels compared to conventional gasoline. However, the results from the British Columbia emissions inspection and maintenance program since 1992 indicate that environmental benefits have not usually been realised in practice.

There are two common routes to acquiring an alternative fuel vehicle. The first option is to convert an existing gasoline-fuelled vehicle to run on either natural gas or propane. The second option is to buy alternative fuel vehicles offered by automotive manufacturers, known as Original Equipment Manufacturer (OEM) vehicles. The majority of in-use natural gas and propane vehicles are aftermarket conversions. Propane and natural gas vehicles can be either mono-fuel or bi-fuel. Mono-fuel vehicles run exclusively on gaseous fuels while bi-fuel models can run on both gaseous fuels and standard gasoline.

This paper summarises and analyses the performance of alternative fuel vehicles over the past eight years from the British Columbia I/M program. It compares the emission trends and failure rates of the alternative fuel and gasoline vehicles. It also compares the emission results of bi-fuel, mono-fuel, OEM and aftermarket vehicles.