Robert Boyle, an Irish chemist noted for his pioneering experiments on the properties of gases, discovered methanol (CH3OH) in 1661. For many years methanol, known as wood alcohol, was produced by heating hardwoods such as maple, birch, and hickory to high temperatures in the absence of air. The most popular modern method of producing methanol, which is also the least costly, is from natural gas (methane) by the direct combination of carbon monoxide gas and hydrogen in the presence of a catalyst. Methanol also can be produced more expensively from oil, coal, and biomass.
Methanol accounted for less than one hundredth of one percent of total transportation fuel consumption in 1999. However, it is a high-octane, clean-burning liquid fuel that has been an important component of rocket fuel, and has been the fuel of choice for Indianapolis-500 race cars since 1965. Internal combustion engine vehicles can operate on methanol alone, but M85 (85% methanol and 15% unleaded gasoline), with an octane rating of 102, is a more common automotive fuel since it requires less dramatic vehicle modifications.
Automobiles that are designed to run on methanol need a few modifications to become flexible fuel vehicles (vehicles that run on either gasoline or methanol). First, for the fuel tank, fuel lines and fuel-injection equipment, the vehicle needs noncorrosive materials such as stainless steel and high-fluorine elastomers. Second, since methanol is a lower energy density fuel, fuel injectors must be larger to provide greater volumes of fuel, and vehicles must be equipped with larger fuel tanks to achieve a range comparable to a gasoline vehicle. Third, a fuel sensor that detects fuel composition is needed to relay information to the on-board computer. And finally, the lower volatility and higher heat vaporization of methanol requires a special starting system for convenient cold weather start-ups.
By 1996, California had about 13,000 cars and 500 buses and trucks running on methanol, which was more methanol vehicles than the rest of the United States combined. The driving force for methanol vehicle growth was stringent California emission regulations designed to improve air quality. Since methanol vehicles cost only marginally more than gasoline-only vehicles, and the combustion of M85 produces less smog-forming and toxic air pollutants than comparable gasoline-powered vehicle—around 30 percent of the non-methane hydrocarbons (HC), 20 percent of carbon monoxide (CO), and 10 percent of the nitrous oxide (NOx) of conventional gasoline engines—fuel-flexible methanol vehicles were seen as a very cost-effective means of improving air quality. However, the near-term future for methanol vehicles looks bleak. Los Angeles had to scrap its methanol transit fleet in the late 1990s because of the corrosive effect of the fuel on the heavy-duty diesel engines. The oil companies also responded to the methanol threat by developing much cleaner-burning reformulated gasoline. Combined with the tremendous advances in vehicle technology, such as improved fuel injection, advanced computer controls, variable valve timing, and electrically heated catalysts, some standard model year 2000 gasoline-powered automobiles not only can meet the California Air Resource Board's Ultra Low Emission Vehicle standards (HC: 0.040, CO: 1.7, NOx: 0.040 grams/mile), but also the proposed Super Ultra Low Emission Vehicle standards (HC: 0.02, CO: 1.0, NOx: 0.010 grams/mile).
In the rest of the United States, the primary use of methanol is as a chemical feedstock and in the synthesis of methyl-t-butyl ether (MTBE), the most widely used gasoline additive that boosts octane and reduces the level of emissions. To reduce carbon monoxide emissions, the Clean Air Act of 1992 designated thirty-nine areas in the United States where gasoline sold from November through February must contain 2.7 percent oxygen. MTBE, with an octane rating of 116, is the primary oxygenate additive. Oil companies favored MTBE over ethanol, which has an octane rating of 108, since gasoline formulated with MTBE runs more smoothly with less knock because of its higher boiling point, and MTBE does not vaporize out of the gas tank as quickly as ethanol. The downside for MTBE, however, is that it adds five to ten cents a gallon to the cost of gasoline and reduces gas mileage by around 10 percent. There have also been concerns about the toxicity of any spilled MTBE that may get into the water supply.
As a fuel, none of the four ways of producing methanol can compete with petroleum at its 1999–2000 price of $15 to $30 a barrel. The per-barrel price of oil would have to surpass $40 for methanol made from natural gas to become a competitive alternative, over $50 if the methanol was produced from coal, and close to $70 if it was made from wood. Although methanol is a cleaner burning fuel than gasoline and diesel fuel, when produced from natural gas, it generates more carbon dioxide emissions (which is suspected of contributing to global warming) than diesel fuel.
Although methanol's future is bleak as a fuel for internal combustion engines, its future is much brighter for fuel cell vehicles. Fuel cell vehicles run on hydrogen, yet due to hydrogen's low energy density, it is expensive to transport and store. Thus, auto makers are looking at ways to extract hydrogen from methanol through a device called a steam reformer. Steam reformers combine methanol with steam and heat to produce hydrogen, carbon dioxide and trace amounts of carbon monoxide (that must be removed by an oxidation reactor downstream of the reformer):
By 1999, General Motors, Daimler-Chrysler, Toyota, and Nissan all had demonstration fuel cell vehicles operating on methanol, with plans to start introducing vehicles into the market by 2005. Auto makers have shown a preference for methanol over gasoline primarily because of the likelihood of the sulfur content in gasoline poisoning some of the catalysts used in the fuel cell.
Nevertheless, methanol still faces a major technological hurdle: the endothermic (requires heat) nature of the methanol steam reformer. Heat must come from an additional reactor to burn some of the fuel or exhaust gases from the fuel cell stack. It also takes time to reach operating temperature, which may be an unacceptable compromise for potential auto buyers accustomed to start-and-go vehicles. Additionally, if methanol for fuel cell vehicles began to capture a significant share of the transportation fuel market, it would require major investments in infrastructure. Gasoline and methanol cannot share the same distribution system since methanol can be highly corrosive and presents a greater fire hazard. And since methanol is much more toxic than gasoline, colorless and nearly odorless, greater precautions are needed to lower the risk of groundwater contamination from leaking storage tanks.
Greene, D. L. (1996). Transportation and Energy. Landsdowne, VA: Eno Transportation Foundation, Inc.
Olah, G. A., and Molnar, A. (1995). Hydrocarbon Chemistry. New York: John Wiley.
Methanol is an organic compound with the chemical form CH3OH. It is also known as methyl alcohol or wood alcohol. Like most alcohols, methanol is very toxic. Its ingestion can cause severe nerve damage leading to blindness, insanity, and death. Methanol can be prepared through destructive distillation of coal , wood and wood products, garbage , sewage sludge , and other forms of biomass . It is an excellent automotive fuel and has long been used to power racing cars. Existing methods of production are still too expensive, however, to make it an economically viable alternative to gasoline in the general market.
meth·a·nol / ˈme[unvoicedth]əˌnôl; -ˌnōl/ • n. Chem. a toxic, colorless, volatile flammable liquid alcohol, CH3OH, originally made by distillation from wood and now chiefly by oxidizing methane. Also called methyl alcohol.