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This paper compares the mass, composition and reactivity towards ozone formation of gasoline and methanol vehicle emissions. Methods used to estimate ozone forming potential include published reactivity scales and the EPA-OZIPM model. Evaluation of the available vehicle emission measurement data does not indicate any ozone benefit for methanol. The data show a wide range in the reactivity of gasoline vehicle VOC emissions. Emissions from vehicles with advanced emission control systems and low mileage have the lowest reactivity. Methanol vehicles emit essentially the same amounts of VOC (on a carbon basis), NOx and CO as gasoline-powered vehicles, and their VOC reactivity fails within the range for gasoline vehicles. When methanol fuels are compared directly with gasoline in flexible fuel vehicles, their VOC emissions have the same or higher reactivity.

Exhaust and evaporative emissions from three flexible/variable fuel vehicles (FFV/VFV) were measured as the vehicles operated on E85 fuel (a mixture of 85% ethanol and 15% gasoline) or on gasoline. One vehicle was a production vehicle designed for ethanol fuels and sold in 1992-93 and the other two vehicles were prototypes which were recalibrated 1992 model year methanol FFV's. The gasolines tested were Industry Average Fuel A and a reformulated gasoline Fuel C2 that met California 1996 regulatory requirements. The gasoline component of Fuel E85 was based on the reformulated gasoline. The major findings from this three-vehicle program were that E85 reduced NOx 49% compared to Fuel A and 37% compared to Fuel C2, but increased total toxics 108% (5 mg/mi) and 255% (20 mg/mi), respectively, primarily by increasing acetaldehyde. The NOx effect was significant for both engine-out and tailpipe emissions.

Blends of up to 20% methanol in gasoline were evaluated in both engine dynamometer and controlled vehicle tests, and in a 50,000 mile road test. Performance comparisons between methanol blends and base gasolines were made in vehicle driveability and vapor lock tendency, engine deposits and wear, fuel economy, exhaust emissions, compatibility with fuel system materials, and phase stability of the blends. Vapor lock tests in six 1974 cars strongly suggested that the vapor lock tendency of methanol blends is greater than would be predicted for gasolines having the same volatility characteristics. Cold start and warm-up driveability of two 1974 cars at 70°F depreciated as methanol concentration increased in base fuels of three volatility levels. These driveability data were found to correlate well, at a given methanol concentration, with fuel volatility characteristics described by means of a new fuel vaporization pressure technique.

Methanol produced from coal or natural gas can be converted over ZSM-5 class zeolite catalyst to high quality gasoline. Process reactions and yields are shown to be viable, thus providing a unique way to manufacture liquid transportation fuels from solid or gaseous energy sources. The hydrocarbon composition and physical properties of the gasoline are very similar to those of conventional petroleum-derived gasolines. No engine or vehicle modifications are required to use it. Laboratory and vehicle tests show the performance characteristics of the finished gasoline to compare very favorably in all aspects with commercial premium gasolines.