U.S. ENVIRONMENTAL PROTECTION AGENCY ERA 400^-92-010
OFFICE OF MOBILE SOURCES
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 gaso-
line 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 prop-
erties (see figures on page 3):
• LOWER VOLATILITY (Figure 1)
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 (Figure 2)
Methanol vapor must be four times more concentrated in air than gasoline vapor for igni-
tion 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 rap-
idly 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
FACT SHEET OMS-8
August, 1994
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• Methanol Fuels and Fire Safety.
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 pos-
sible to reduce the amount of methanol required to travel a distance equivalent to that trav-
eled 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.
For More Information:
The Office of Mobile Sources is the national center for research and policy on air
pollution from highway and off-highway motor vehicles and equipment. You
can write to us at the EPA National Vehicle and Fuel Emissions Laboratory,
2565 Plymouth Road, Ann Arbor; MI 48105. Our phone number is (313) 668-4333.
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Methanol Fuels and Fire Safety.
Fuel-related vehicle fires,
deaths, and injuries
Fuel fire fatality zones"
80% -
60% -
40% -
20% -
n,
CH Gasoline (1986
FEMA & NHTSA
data)
D Methanol (EPA
projection)
Gasoline
fires
deaths injuries
*The zone in which 1% or more of bystanders would be
killed by fire, assuming a fuel pool ten meters in diameter.
Makes little vapor (evaporates slowly)
Needs lots of vapor
to burn
Fire zone is confined; fires
much less likely
Needs little vapor
to burn
Makes lots of vapor (evaporates fast)
Fire zone is broad; fires much
more likely
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