Gasoline compared with methanol

Compared with other alternative motor fuel options (reformulated gasoline, compressed or liquefied natural gas, ethanol from corn or coal, methanol and electricity), propane has the lowest greenhouse gas emissions except for natural gas. According to a 1998 study by the Institute of Transportation Studies, greenhouse emissions from propane vehicles arc 21.8 percent less than from gasoline or diesel. 

One of the considerations regarding the use of methanol as a fuel is that it emits higher amounts of formaldehyde, which is a contributor to ozone formation and a suspected carcinogen, compared to gasoline. Proponents of methanol dispute this, saying that one-third of the formaldehyde from vehicle emissions actually comes from the tailpipe, with the other two-thirds forming photochemically, once the emissions have escaped. They state that pure methanol vehicles produce only one tenth as much of the hydrocarbons that are photochemically converted to formaldehyde as do gasoline automobiles. 

Based on the tuned models, equipment performance could be evaluated and compared with design. The models could then be readily adapted to simulate an additional process fired heater (to unload the methanol superheater) and to evaluate it s inpact on the overall MTG unit performance. Multiple case studies were performed to determine optimum heater size with regard to maximising heat recovery and providing unit heat balance flexibility. The additional heat balance flexibility allows the ZSM-5 catalyst outlet temperature to be reduced hence maximising gasoline yield. 

In order to reduce CO formation, the reformer should operate with excess of water and at lower temperature. Compared with all other common liquids, such as gasoline and ethanol, methanol is a promising liquid fuel candidate as it can be reformed into hydrogen at a relatively low temperature (about 250 °C). The usual reforming temperature for other liquids is higher (450-900 °C), which results in much higher CO concentration in the product gas. 

Experience gained from the observation of oil seals in the automotive industry indicated that blends of methanol and gasoline can have a deleterious effect on many elastomers currently used in automotive oil seals. The effect of methanol as a constituent (15%) in an aromatic fuel is greater than that of other higher alcohols, e.g. ethanol, as is shown in Fig. 7. This should be compared with the swelling behaviour of the same range of elastomers in pure 42% aromatic fuel (Fig. 8). ... 

In summary, the difficulty of ignition, low-temperature flame, low radiant heat output, and ease of extinguishing together mean that compared with gasoline, methanol fires are less likely to occur and less damaging when they do occur. 

Alcohol Production. Studies to assess the costs of alcohol fuels and to compare the costs to those of conventional fuels contain significant uncertainties. In general, the low cost estimates iadicate that methanol produced on a large scale from low cost natural gas could compete with gasoline when oil prices are around 140/L ( 27/bbl). This comparison does not give methanol any credits for environmental or energy diversification benefits. Ethanol does not become competitive until petroleum prices are much higher. 

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