Emissions and Fuel Economy Tests of a Methanol Bus with a 1988 DDC Engine

A methanol-fueled transit bus with a 1988-technology Detroit Diesel Corporation (DDC) 6V-92TA engine was chassis dynamometer tested using steady-state and transient cycles to determine exhaust emissions and fuel economy. With chemical-grade methanol (M100), the bus had lower particulate, NO_x, and heavy aldehyde emissions than the comparable (though older) diesel bus; however, formaldehyde and organic emissions were higher. Two other approaches were tried: methanol with 15% added gasoline (M85) and an exhaust catalyst (with M100). Both reduced formaldehyde and organic emissions relative to M100 alone, but they both increased heavy aldehyde emissions. The exhaust catalyst also reduced particulate emissions.