Methanol Vehicle Exhaust Emissions

It is fundamental to the establishment of the ILEV concept that a reduction in hydrocarbon emissions results in a corresponding reduction in ambient ozone levels, a view not universally shared. For example, in areas where there is a high concentration of natural hydrocarbons in the atmosphere or where there is a low NO-hydrocarbon ratio, hydrocarbon reductions will have little effect. However, there is sufficiently widespread applicability of beneficial effects arising from lower hydrocarbon emissions, not least when air toxics, such as benzene or 1,2-butadiene, are concerned, that the national ILEV designation is another worthwhile step on the road to clean air. 

The impact of ILEV on methanol fuel is dramatic because M85 or any similar fuel methanol formulation is effectively excluded from consideration. The ILEV concept is a carefully constructed transportation control measure designed to encourage the swifter introduction of dedicated vehicles, particularly those fueled by Ml00 or CNG, provided such vehicles can meet the LEV exhaust emissions standards set by California and the ILEV evaporative emissions standard set by the EPA for the fuel and fuel supply system. The EPA estimates that the ILEV standards offer triple the emissions reductions of a LEV and double those of ULEV [13]. Of course, such estimates beg the question of equivalen- 

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Although liquid hydrogen, LH2, can be used as a fuel source, much of the recent fuel cell research is focusing on the partial oxidation of methanol, natural gas, ethanol, or gasoline to produce the necessary hydrogen. Catalysts that aid in the partial oxidation of these fuels yields a readily available, rich source of hydrogen. Water is the primary exhaust emission produced by fuel cell powered vehicles. If a carbon-based fuel source is utilized, then a carbon-containing by-product will also be produced. 

Figure 6 shows data for four vehicles operated on gasoline and M85, two having an electrically heated catalyst (EHC). The two vehicles equipped with EHC both showed low values ol NMOG and estimated ozone production. These data seem to indicate that methanol vehicles result in less ozone than comparable gasoline veliides. However, the data only include exhaust emissions and not evaporative or running losses. These later sources of emissions should be lower using methanol because of the lower reactivity of the alcohols. 

Fig. 2. CEC methanol-fueled vehicle exhaust profile for (a) HC, hydrocarbons (b) NO and (c) CO. Solid line represents State of California standard maximum emissions. Methanol HC emissions are calculated as CH g5 and not corrected for flame-ionization detector response.

What are the advantages and disadvantages of switching to methanol-powered vehicles Methanol burns more cleanly than gasoline, and levels of troublesome pollutants such as carbon monoxide, unreacted hydrocarbons, nitrogen oxides, and ozone are reduced (Chapter 4). However, there is concern about the higher exhaust emissions of carcinogenic formaldehyde from methanol-powered vehicles. Since the number of methanol-powered vehicles is limited, it is still difficult to assess the extent to which these formaldehyde emissions will contribute to the total aldehyde levels from other sources. 

Finally, formaldehyde emissions are frequently raised as an issue of particular environmental importance for methanol vehicles on two counts first, there is concern for formaldehyde as an air toxic, and second, there is its role as a highly reactive ozone precursor. Formaldehyde is a gas that is naturally present at low concentrations in the atmosphere, originating as an intermediate in the slow photooxidation of various organic compounds released into the environment from a variety of sources. As a low-level constituent of engine exhaust, it is also emitted directly into the air by both diesel and gasoline vehicles. 

Iceland may start with methanol powered PEM vehicles and vessels. The University of Iceland is involved in research on the production of methanol (CH3OH) from hydrogen combined with carbon monoxide (CO) or C02 from the exhaust of aluminum and ferrosilicon smelters. This would capture hundreds of thousands of tons of CO and C02 released from these smelters. If this is combined with hydrogen generated from electrolysis using renewable power, Iceland could cut its greenhouse gas emissions in half. 

Fig. 5 - Exhaust gas PAH emissions of the VW/Audi test fleet in the Federal Test Procedure (FTP). On the abscissa the cars are depicted with regard to the parameters engine displacement, fuel, and exhaust control device. Columns in the second horizontal direction represent measuring values for the PAH of different vehicles of the same type. Each column represents the mean value of three re-petetive measurements of the same vehicle. For each car group two or three different cars were measured in most cases. TWC = Three Way Catalyst M 15 = methanol-gasoline blend fuel (15 % methanol) M 100 = pure methanol fuel...

Fig. 8 - Exhaust gas PAH emissions of the VW/Audi test fleet in three different test procedures. Each block represents the resulting mean value of the PAH emissions from all vehicles of one type. Columns in the second horizontal direction show in this Figure the dependency on the different test procedures. The first block of the group shows the FTP test, the second block displays the FET test, and the third block represents the ECE test. ECE test measurements for the gasoline engine 1.3 1 and the methanol (M 100) engine 1.6 1 have not yet been performed...

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