Methanol Production

There are 18 methanol production plants in the United States with a total annual capacity of over 2.6 billion gallons per year. Worldwide, over 90 methanol plants have the capacity to produce over 11 billion gallons of methanol annually. The global methanol industry generates $12 billion in economic activity each year, while creating nearly 100,000 jobs.

The typical feedstock used in the production of methanol is natural gas. Methanol also can be made from renewable resources such as wood, municipal solid wastes and sewage. The production of methanol also offers an important market for the use of flared natural gas.

In a typical plant, methanol production is carried out in two steps. The first step is to convert the feedstock natural gas into a synthesis gas stream consisting of CO, CO2, H2O and hydrogen. This is usually accomplished by the catalytic reforming of feed gas and steam. Partial oxidation is another possible route. The second step is the catalytic synthesis of methanol from the synthesis gas. Each of these steps can be carried out in a number of ways and various technologies offer a spectrum of possibilities which may be most suitable for any desired application.

Conventional steam reforming is the simplest and most widely practiced route to synthesis gas production:

2 CH4 + 3 H2O _ CO + CO2 + 7 H2 (Synthesis Gas)

CO + CO2 + 7 H2 _ 2 CH3OH + 2 H2 + H2O

This process results in a considerable hydrogen surplus, as can be seen.

If an external source of CO2 is available, the excess hydrogen can be consumed and converted to additional methanol. The most favorable gasification processes are those in which the surplus hydrogen is “burnt” to water, during which steam reforming is accomplished by partial oxidation:

CH4 + _ O2 _ CO + 2 H2 _ CH3OH

CH4 + O2 _ CO2 + 2 H2

The carbon dioxide and hydrogen produced in the last equation would then react with an additional hydrogen from the top set of reactions to produce additional methanol. This gives the highest efficiency, but may be at additional capital cost.

Unlike the reforming process, the synthesis of methanol is highly exothermic, taking place over a catalyst bed at moderate temperatures. Most plant designs make use of this extra energy to generate electricity needed in the process.

What is Methanol? Methanol is the simplest alcohol, containing one carbon atom. It is a colorless, tasteless liquid with a very faint odor and is commonly known as "wood alcohol."

Methanol Chemical Formula

Methanol is one of a number of fuels that could substitute for gasoline or diesel fuel in passenger cars, light trucks, and heavy-duty trucks and buses.

Why Consider Methanol?

Methanol's physical and chemical characteristics result in several inherent advantages as an automotive fuel:

LOW POLLUTION

Emissions from methanol cars are low in reactive hydrocarbons (which form smog) and in toxic compounds. Methanol-fueled trucks and buses emit almost no particulate matter (which cause smoke and odor, and can also be carcinogenic), and much less nitrogen oxides than their diesel-fueled counterparts.

FUEL SUPPLY OPTIONS

Methanol can be manufactured from a variety of carbon-based feedstocks such as natural gas, coal, and biomass (e.g., wood). Use of methanol would diversify the country's fuel supply and reduce its dependence on imported petroleum.

FIRE SAFETY

Methanol is much less flammable than gasoline and results in less severe fires when it does ignite.

HIGH PERFORMANCE

Methanol is a high-octane fuel that offers excellent acceleration and vehicle power.

ECONOMICALLY ATTRACTIVE

With economies of scale, methanol could be produced, distributed, and sold to consumers at prices competitive with gasoline.

Current Methanol Uses

Because of its outstanding performance and fire safety characteristics, methanol is the only fuel used in Indianapolis-type race cars. Following a series of methanol vehicle development and demonstration programs throughout the 1980's, a limited number of methanol passenger cars and buses are now commercially available. There are approximately 14,000 methanol passenger cars in use, mostly in Federal and private fleets, and about 400 methanol buses in daily operation, mostly in California.

Methanol is used in a number of consumer products, including paint strippers, duplicator fluid, model airplane fuel, and dry gas. Most windshield washer fluids are 50 percent methanol.

Is Methanol Poisonous?

Yes. As with many other fuels, methanol can be highly toxic and should never be taken orally. A few teaspoons of methanol can cause blindness and a few tablespoons can be fatal, if the exposure is not treated.

It should be noted that the human body can metabolize and eliminate low concentrations of methanol with no ill effects. (Methanol is present in many cooked vegetables, and the artificial sweetener in diet soft drinks breaks down into methanol during digestion.) Methanol becomes poisonous only when it overwhelms the body's capacity to remove it. Toxic effects do not occur until several hours after exposure. Effective antidotes to methanol poisoning are readily available and can be administered during this interim period.

Methanol Fuels and Fire Safety

Vehicle Fire Risk

In 1986, there were 500,000 vehicle fires and 1,400 vehicle fire fatalities in the United States. Gasoline was the first material to ignite in 180,000 of these fires and many of the other fires ultimately involved gasoline. Gasoline-ignited fires in 1986 involving cars, buses, or trucks resulted in 760 deaths, 4,100 serious injuries, and $215 million in property damage. Projections indicate that casualties would drop dramatically if methanol were substituted for gasoline as the country's primary automotive fuel. Looking just at vehicle fires in which gasoline is the first material to ignite, a switch to methanol could save an estimated 720 lives, prevent nearly 3,900 serious injuries, and eliminate property losses of millions of dollars a year. Methanol's fire safety advantage over gasoline stems from several physical and chemical properties (see figures on page 3):

LOWER VOLATILITY

Methanol does not evaporate or form vapor as readily as gasoline does. Under the same conditions, exposed gasoline will emit two to four times more vapor than will exposed methanol.

HIGHER FLAMMABILITY REQUIREMENT

Methanol vapor must be four times more concentrated in air than gasoline vapor for ignition to occur.

LOWER VAPOR DENSITY

Gasoline vapor is two to five times denser than air, so it tends to travel along the ground to ignition sources. Methanol vapor is only slightly denser than air and disperses more rapidly to non-combustible concentrations.

LOWER HEAT RELEASE RATE

Methanol burns 25 percent as fast as gasoline and methanol fires release heat at only one-eighth the rate of gasoline fires.

These properties together make methanol inherently more difficult to ignite than gasoline and less likely to cause deadly or damaging fires if it does ignite. Methanol is the fuel of choice for Indianapolis-type race cars, in part because of its superior fire safety characteristics.

Other Fire Issues

Pure methanol burns with a light blue flame that is not easily seen in bright sunlight. It is possible, though highly unlikely, that spectators or firefighters might fail to notice the heat and unknowingly walk into a methanol fire. In the great majority of vehicle fires, however, burning materials other than fuel (such as engine oil, upholstery, paint, etc.) would produce both smoke and visible flames. In addition, a chemical could be mixed with methanol fuel to provide flame luminosity. Research is under way to identify potential additives.

Unlike gasoline, methanol can ignite at ambient temperatures in enclosed spaces such as fuel tanks (gasoline produces too much vapor to ignite in enclosed spaces). But this property of methanol is unlikely to cause vehicle fires or ''explosions" in either collision or non-collision situations. Explosions occur in collisions when the fuel tank ruptures and spilled gasoline bursts into flame. Again, this is much less of a risk with methanol than with gasoline. In non-collision situations, fuel tanks tend to be isolated from ignition sources. Finally, simple vehicle design modifications to methanol vehicles will even further reduce the chance of fuel tank ignition. These changes include use of materials that prevent flames from spreading through the fuel tank and modifications to further isolate the tank from sparks and other ignition sources.

Fuel Distribution Issues

Methanol's energy content on a per-gallon basis is roughly half that of gasoline. Motorists would need about twice as much methanol as gasoline to travel an equivalent number of miles, and nearly twice as much methanol would have to move through the fuel distribution system to accommodate them. (If vehicles were optimized for methanol, it would be possible to reduce the amount of methanol required to travel a distance equivalent to that traveled on one gallon of gasoline.)

If methanol were as flammable as gasoline, the doubling of fuel transport would result in more fires. However, methanol holds such inherent fire safety advantages over gasoline that the opposite should occur. Deaths, injuries, and damage due to fires in the fuel distribution system should in fact decline, despite the increase in fuel transportation.

Fire Safety Comparison Chart: