This paper provides a summary review of several comparative studies on the emission characteristics of methanol- and diesel-fueled buses. In order to facilitate comparison, the emissions data at idle and various driving cycles are presented on an hourly and/or per-mile basis. The results suggest that the substitution of methanol-fueled buses for clean diesel buses is not likely to result in net air-quality improvements during low-speed operations in an urban environment. Under these conditions, the negative effects of increases in carbon monoxide, formaldehyde, and hydrocarbons may offset the positive effects of particulate emissions reduction. However, for higher average driving speeds, the results to date are more promising, suggesting that methanol-fueled buses with well-operating catalysts offer net emissions benefits when substituted for old and recent-model diesel buses. This paper makes no attempt to weight emissions or to estimate air quality and does not estimate net emissions benefits. It is shown that pollutant-specific emissions from the test methanol vehicles are highly variable with average speed and are dependent on the engine technology and the emission-control devices used. It is also shown that the change in emissions resulting from the substitution of a methanol bus for a diesel bus can often be positive or negative for a single pollutant, depending on how the buses are driven. In general, methanol does not ignite under compression as easily as does diesel fuel, leading to relatively poor emissions performance by methanol buses when those buses spend a great deal of time at idle or at low engine load and vehicle speed. 18 refs., 19 figs., 4 tabs.
Comparison of emissions of transit buses using methanol and diesel fuel
1989
33 pages
Report
Keine Angabe
Englisch
Air Pollution & Control , Road Transportation , Environmental Studies , Fuels , Diesel Fuels , Emission , Methanol Fuels , Buses , Air Quality , Carbon Monoxide , Chemical Analysis , Comparative Evaluations , Compiled Data , Environmental Effects , Formaldehyde , Health Hazards , Hydrocarbons , Ketones , Nitrogen Oxides , Particulates , Performance Testing , Platinum , Pollutants , Recommendations , Standards , Technology Assessment , Temperature Effects , Toxic Materials , Meetings , Tables(data) , Exhaust gases , EDB/290300 , EDB/320203 , EDB/540120
Emissions from methanol, ethanol, and diesel powered urban transit buses
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