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Two additive blends proposed for improving the flame luminosity in neat methanol fuel were investigated to determine the effect of these additives on the exhaust emissions in a dual-fueled Volkswagen Jetta. The two blends contained 4 percent toluene plus 2 percent indan in methanol and 5 percent cyclopentene plus 5 percent indan in methanol. Each blend was tested for regulated and unregulated emissions as well as a speciation of the exhaust hydrocarbons resulting from use of each fuel. The vehicle exhaust emissions from these two fuel blends were compared to the Coordinating Research Council Auto-Oil national average gasoline (RF-A), M100, and M85 blended from RF-A. Carter Maximum Incremental Reactivity Factors were applied to the speciated hydrocarbon emission results to determine the potential ozone formation for each fuel. Toxic emissions as defined in the 1990 Clean Air Act were also compared for each fuel.

Neat methanol fuel (M100) has many advantages for achieving low emission levels as an automotive fuel, but there are several items that require attention before this fuel can replace conventional fuels. One item involves the low flame luminosity of methanol. An extensive literature search and laboratory evaluation were conducted to identify potential additive candidates to improve the luminosity of a methanol flame. Potential compounds were screened based on their concentration, luminosity improvement, and duration of luminosity improvement during the burn. Three compounds were found to increase the flame luminosity for segments of the burn at relatively low concentrations: toluene, cyclopentene, and indan. In combination, these three compounds markedly improved the luminosity of methanol throughout the majority of the burn. The two combinations were 1) 4 percent toluene plus 2 percent indan and 2) 5 percent cyclopentene plus 5 percent indan in methanol.

Engine durability refers to the ability of an engine to function properly and reliably over an extended period of time. Engine durability is a major remaining technical hurdle prior to expanding the use of methanol fuel. This paper will present engine durability data derived from the California Energy Commission's continuing Alcohol Fleet Test Program, review this data in relationship to previously reported engine durability information, discuss some of the possible reasons for observed effects, and suggest design considerations for further improvement in methanol engine durability.